Best 10W30 Oil for Generator: Top Picks for Reliable Power

Most people assume any 10W30 oil will do for a generator, but that overlooks some crucial engine demands unique to these machines. Generator engines face consistent, high-heat operation, which can quickly degrade standard oils designed for vehicles.

The best 10W30 oil for a generator must possess excellent thermal stability, superior wear protection, and viscosity control tailored for small engines under sustained load.

Many oils marketed as multipurpose fall short on these key requirements, leading to reduced engine life and performance hiccups. Choosing the right formula makes all the difference, so let’s look at options that truly match these needs.

Choosing the Best 10W30 Oil for Optimal Generator Performance

Ensuring your generator runs smoothly requires the right 10W30 oil that balances protection, durability, and efficiency. Explore top engine oils formulated to keep your equipment operating at peak levels.

Mobil 1 High Mileage Full Synthetic Motor Oil 10W-30 for Enhanced Engine Care

Protecting engines with high mileage demands more than ordinary oil. Mobil 1’s advanced formulation is engineered to support vehicles clocking over 75,000 miles, extending oil change intervals up to 10,000 miles while maintaining peak performance. Its signature Triple Action Formula actively cleans and shields engine components, ensuring outstanding performance under diverse conditions.

Meeting modern ILSAC GF-6 specifications, this full synthetic blend combats low-speed pre-ignition and minimizes timing chain wear, problems often overlooked in aging engines. You’ll appreciate how it maintains engine cleanliness and improves fuel efficiency, a rare dual benefit.

Operating flawlessly from -30°F cold starts to enduring internal temperatures up to 500°F, this oil offers superior thermal protection. Its capacity to lower engine heat helps prevent sludge buildup, a common culprit behind reduced engine life.

Mobil 1 stands out for delivering smooth, quiet operation along with its robust protective qualities. Its consistency and performance make it a dependable choice for any universal fit car application needing reliable lubrication in various climates.

Best for: Vehicle owners seeking full synthetic oil that supports extended mileage, protects aging engines, and enhances fuel economy.

Pros:

• Extended oil change intervals reduce maintenance frequency
• Triple Action Formula cleans, protects, and improves engine efficiency
• Thermal stability from extreme cold to high heat
• Meets ILSAC GF-6 standards for advanced engine protection
• Compatible with high-mileage vehicles for universal fit applications

Cons:

• May feel pricier compared to conventional oils for some budgets

Shell Rotella T6 Full Synthetic 10W-30 Engine Oil for Heavy-Duty Protection, 3 Gallons

Handling engines exposed to a wide range of temperatures demands a lubricant that adapts seamlessly. Shell Rotella T6 blends synthetic technology with a 10W-30 viscosity grade to deliver consistent performance whether you’re facing bitter cold starts or high-heat operation.

Harness the power of Triple Protection Plus technology, which guards against engine wear, deposit accumulation, and oil breakdown, extending the life of diesel and gasoline engines under heavy load. Its advanced formula surpasses API CJ-4 standards by 33%, keeping critical engine parts remarkably clean.

Designed for durability, the oil’s extended drain intervals mean you’ll spend less time on maintenance and more uptime on your equipment. The low-ash composition also plays a vital role in maintaining emissions system compatibility, helping engines meet modern environmental standards without sacrificing fuel economy.

Shell’s expertise ensures this motor oil achieves exceptional oxidation resistance, contributing to reliable performance through rigorous workdays. Its universal fit accommodates trucks, generators, and agricultural equipment alike, making it a flexible choice backed by robust specifications and OEM approvals.

Best for: Operators requiring reliable engine protection in machines running under varying temperatures and heavy-duty conditions.

Pros:

• Advanced synthetic formula reduces engine wear effectively.
• Extended drain capability increases maintenance intervals.
• Excellent performance in both cold starts and high-heat environments.
• Low-ash technology supports exhaust after-treatment systems.
• Meets or exceeds multiple industry and OEM standards.

Cons:

• May be more than needed for light-duty or small engines.

Castrol GTX 10W-30 Motor Oil – Advanced Engine Protection, 5-Quart Container

Facing the challenge of engine wear and sludge buildup, finding the right lubricant can feel overwhelming. Castrol GTX 10W-30 offers a time-tested formula designed to protect engines from the inside out. The advanced blend minimizes oil breakdown due to heat, preserving viscosity even in demanding conditions.

Experience fewer maintenance concerns thanks to this oil’s superior defense against sludge formation, a common issue that degrades engine performance over time. Premium base oils combined with anti-wear additives help keep your engine running smoother and last longer.

Maintaining oil levels becomes easier as this formulation reduces oil consumption, supporting more efficient engine operation. Castrol’s commitment to quality means the product meets rigorous specifications, including API SP, SN Plus, and ILSAC GF-6 standards.

Packaged in a convenient 5-quart size, it suits a variety of automotive service needs with a universal fit. Incorporating Castrol’s decades of expertise ensures you get trusted, consistent protection for your engine’s longevity.

Best for: Vehicle owners wanting reliable and durable lubrication for engines exposed to regular wear and thermal stress.

Pros:

• Advanced protection against thermal and viscosity breakdown
• Prevents engine sludge for cleaner performance
• Formulated with premium base oils and anti-wear additives
• Helps reduce oil consumption for longer maintenance intervals
• Meets high automotive industry standards for quality

Cons:

• May not offer the extended benefits of full synthetic oils for some users

Pennzoil 10W-30 Motor Oil – Reliable Engine Protection for Cars and Trucks

Keeping your engine running smoothly often hinges on the right lubrication that can tackle dirt and wear head-on. Pennzoil’s 10W-30 motor oil is formulated to maintain clean engine surfaces and enhance responsiveness even in daily driving conditions.

Delivering proven wear protection, this oil helps guard critical components against friction that sabotages performance. Its advanced formula prevents harmful contaminants from forming deposits that slow your engine down over time.

Compatible with engine seals and fully blending with all conventional oils, it fits seamlessly into diverse gasoline engines across cars, SUVs, light vans, and trucks. The brand’s reputation ensures reliability through its adherence to API SP and ILSAC GF-6A standards.

Equipped for a broad spectrum of temperatures and operating conditions, Pennzoil provides consistent lubrication to support engine durability and smooth power delivery. Smartly packaged in a 1-quart size, it suits on-the-go top-ups or routine maintenance needs.

Whether you’re managing a daily driver or small equipment, Pennzoil stands out for its balance of engine cleanliness and component protection, giving you dependable performance without fuss.

Best for: Vehicle owners and outdoor equipment enthusiasts seeking a sturdy, all-around lubricant that keeps engines well-tuned and protected under varied conditions.

Pros:

• Formulated to maintain clean engine internals
• Provides effective wear and friction protection
• Compatible with a wide range of gasoline engines
• Meets current industry performance standards
• Suitable for multiple vehicle types and light equipment

Cons:

• May not offer synthetic oil level performance for extreme conditions
• Limited container size might require frequent purchases for heavy users

Honda Genuine 10W30 Motor Oil Quart Pack for High-Performance Small Engines

When your small engine demands unwavering reliability, opting for an oil engineered to withstand intense conditions becomes essential. Honda’s formulation incorporates sheer-stable polymer additives paired with premium base stocks, ensuring the oil maintains its viscosity even under thermal stress.

Meeting stringent API SM standards, this blend is specifically tailored to support the unique demands of power equipment like generators and lawn mowers. Its composition delivers enhanced protection against engine wear and helps sustain long-term engine health.

Each quart in this pack offers compatibility with a wide range of small gas-powered machines, providing consistent lubrication performance that reduces the risk of operational disruptions. The flash point at 200°C further confirms its resilience to high engine temperatures.

Honda’s direct involvement in designing this oil offers peace of mind for those who rely on their equipment during critical times. Its robust formulation actively helps preserve engine integrity through extreme conditions and extended use.

Best for: Those who require a dependable oil solution for small engines like generators, seeking lasting protection and stable performance.

Pros:

• Formulated with high-quality base stocks and polymer additives
• Meets or exceeds API SM service classifications
• Designed specifically for Honda power equipment and similar small engines
• Maintains viscosity and thermal stability under demanding conditions
• Pack of two quarts offers convenient maintenance supply

Cons:

• For some users, could represent a higher upfront investment compared to conventional oils

Maintenance 2 PK Synthetic Blend Motor Oil 10W30 for Small Engines and Generators

Keeping your small engine running smoothly is easier with the right formula in your crankcase. Balancing protection and performance, this 10W-30 synthetic blend caters specifically to the demands of generators, lawn mowers, and similar equipment. It offers reliable viscosity that adapts well across temperature fluctuations to maintain steady operation.

Formulated with a blend that supports heavy-duty use, the oil reduces friction and wear during those extended runtime periods. Maintenance’s attention to compatibility means it universally fits most engines needing this grade, including many Kohler models, ensuring seamless integration without compromise.

Featuring a weight around 4 pounds per package, the two-quart set provides ample supply for seasonal upkeep or multiple oil changes. It’s designed to guard engine components against heat and deposits, promoting cleaner engine internals and longer motor life. A smoother-running engine also translates into enhanced efficiency and fewer unexpected breakdowns.

Trusted by users who value economical yet dependable care, this blend stands out as a practical investment for your equipment’s longevity. The brand Maintenance is recognized for delivering oils that meet rigorous standards while offering noticeable performance benefits you can rely on.

Best for: Owners of portable generators, lawn mower enthusiasts, and anyone requiring steady, universal 10W-30 oil to maintain smaller engine equipment.

Pros:

• Specifically suited for small engines like generators and mowers
• Engineered synthetic blend enhances wear resistance and stability
• Universal fit for a broad range of equipment including Kohler engines
• Comes in a convenient two-pack for multiple changes or bulk use
• Helps maintain cleaner engine internals and improved lifespan

Cons:

• May not be ideal for heavy-duty or commercial-grade engines needing specialized oils
• Could require careful disposal or recycling of used oil per local regulations

Honda Power Equipment 10W-30 Motor Oil – 1 Quart for Reliable Engine Care

Maintaining peak engine performance often hinges on the quality of oil you choose, especially when operating outdoor power equipment. The Honda Power Equipment 10W-30 Motor Oil offers a blend formulated specifically to meet the demands of Honda gasoline engines, addressing their unique lubrication needs.

Offering consistent viscosity of 10W-30, it ensures efficient flow across a wide temperature range, reducing engine wear and improving startup smoothness in various climates. The oil’s high flash point of 200°C signals its stability under heat, helping maintain engine cleanliness and extending motor life.

Packaged in a convenient 1-quart bottle, this oil supports easy handling and precise measurement for small engines such as those on ATVs, UTVs, and generators. With Honda’s trusted standards backing it, expect a product that works seamlessly with equipment built for durability and performance.

The formulation also addresses concerns some users have with generic oils that may not suit air-cooled or specialized small engines, providing peace of mind for those keen on preserving optimal engine function. Its targeted design minimizes sludge buildup and maximizes protection during engine operation.

Honda’s reputation for quality reflects through this motor oil, offering a straightforward and efficient solution for those looking to extend the life and reliability of their small engines without compromise.

Best for: Operators of small gasoline engines requiring tailored lubrication to maintain power and efficiency under regular use.

Pros:

• Formulated specifically for Honda gasoline engines
• Stable 10W-30 viscosity ensures smooth operation across temperatures
• High flash point promotes engine cleanliness and durability
• Convenient 1-quart bottle for easy oil changes
• Protects air-cooled engines from sludge and wear

Cons:

• May be more specialized than some users require for general-purpose applications

Valvoline Advanced Full Synthetic 10W-30 Motor Oil for Superior Engine Defense

Every engine faces threats from wear, heat, friction, and harmful deposits that silently degrade performance over time. Valvoline tackles these challenges head-on with its advanced full synthetic formula, engineered to deliver 40% enhanced wear protection beyond typical industry benchmarks. It’s not just about lubrication — it’s about extending the life and reliability of your engine.

Using superior detergents, this blend fights buildup and mineral deposits that can sap efficiency and power. With 24 times stronger defense against water intrusion compared to leading synthetic oils, rust and corrosion are less of a concern, ensuring pivotal parts stay cleaner and longer-lasting.

Designed to meet and surpass rigorous standards like ILSAC GF-6A and API SP, this motor oil adapts to extreme conditions, stabilizing viscosity even under temperature swings typical of frequent starts, stops, and idling periods common in generator operation. Incorporating Valvoline’s trusted heritage brings the confidence of American engineering to every quart.

Choosing Valvoline means opting for a lubricant that proactively shields vital components, promotes smoother operation, and guards against premature breakdown. Its balanced 10W-30 grade is versatile for many engines seeking endurance without compromise.

Best for: Those relying on steadfast, high-performance oil to maintain generators and other machinery during demanding use or intermittent operation.

Pros:

• 40% better protection against engine wear than standard oils
• Strong resistance to water-induced rust and corrosion
• Advanced cleaning agents reduce harmful engine deposits
• Meets multiple modern performance specifications
• Full synthetic formula designed for temperature stability

Cons:

• May be more than needed for small, low-use equipment
• Single quart size might require multiple purchases for larger engines

Yamaha Yamalube Premium Golf Car and Generator Engine Oil 10W-30 – 1 Quart

Frequent start-ups and steady loads can quickly wear down engine oil not designed for such demanding tasks. A mineral base combined with a specialized additive system tackles the unique challenges faced by small engines used in recreational and power generation equipment.

Designed with the pressures of both golf cars and generators in mind, Yamaha’s formulation ensures consistent lubrication even under constant operational stress, helping extend engine life. The 10W-30 viscosity grade makes it adaptable to various temperatures, maintaining reliable flow and protection from cold starts to warm running conditions.

Engineers at Yamaha have crafted this oil to provide a universal fit that meets the rigorous demands of different small engine models without compromising performance. The 1-quart container size allows for easy handling and precise application, minimizing waste during maintenance.

With its engine-specific tuning, this oil speaks directly to the needs of your equipment, reducing friction and wear during continuous use. Its trusted brand reputation adds confidence that your engine is getting care tailored to its operational rhythm.

Best for: Operators maintaining golf cars and backup power systems who want dependable, engine-matched protection for frequent and steady-use scenarios.

Pros:

• Formulated with mineral base and expert additives for small engine stress
• SAE 10W-30 grade offers versatile temperature performance
• Specifically built for golf car and generator engine conditions
• Universal compatibility across multiple vehicle makes
• Compact 1-quart packaging for controlled use

Cons:

• May be priced higher than generic oils due to specialized formulation

Royal Purple 10W30 Synthetic Motor Oil – Premium Protection and Fuel Efficiency, 1 Quart

Ensuring reliable performance during varied generator workloads demands more than just any lubricant. Royal Purple delivers a specially formulated synthetic motor oil designed to enhance fuel efficiency while providing superior wear protection even under demanding conditions.

Recognizing that many oils struggle with fuel blends containing ethanol, this formulation offers improved compatibility, guarding your engine parts from accelerated wear. The oil’s advanced composition also supports better corrosion resistance, making it a practical choice to help extend your generator’s service life.

Protecting sensitive emission systems comes standard—this oil is engineered to safeguard catalytic converters, which often face degradation from inferior lubricants. Its mid-range viscosity balances adequate flow at startup and strong film strength when running, optimizing mechanical efficiency.

Produced by Royal Purple, a brand known for cutting-edge synthetic technology, this oil fits a wide array of engines requiring a 10W-30 grade. The 1-quart size makes it ideal for precise refills without waste, supporting consistent maintenance routines.

Choose lubricant designed for durability, efficiency, and protection, giving your equipment the performance edge it deserves.

Best for: Small engine operators seeking extended oil life and enhanced fuel economy for portable power machines.

Pros:

• Better wear protection to extend engine life
• Increased fuel efficiency to optimize operation costs
• Superior corrosion resistance for durable performance
• Compatibility with ethanol-blended fuels
• Protects catalytic emission systems from damage

Cons:

• Single quart packaging might require multiple purchases for larger capacities
• Premium formulation may be priced higher than conventional oils for some users

ULTRA 1PLUS SAE 10W-30 Motor Oil for Extended Engine Protection and Performance

Maintaining engine health during varying temperature extremes demands a lubricant designed for reliable performance. ULTRA 1PLUS SAE 10W-30 motor oil steps in with consistent viscosity that ensures smooth operation whether the engine faces a cold start or intense heat. Its formulation supports engines that operate under both everyday and rigorous conditions without compromising durability.

Expect cleaner engine internals thanks to a proprietary blend that prevents harmful deposits and sludge buildup. This reduces wear and tear, allowing the internal components to function efficiently longer between maintenance intervals. An added benefit is enhanced emission system support, which helps reduce exhaust pollutants without sacrificing power.

Longer service intervals are achievable due to the oil’s resilient nature, designed to maintain protective qualities for an extended timeframe. This translates to fewer oil changes and lowered upkeep costs, which is especially valuable for equipment used intermittently like generators. ULTRA 1PLUS integrates advanced features without the need for synthetic formulations, offering a balanced approach to engine care.

Engineered by Ultrachem LLC, this motor oil aligns with API SL specifications to deliver reliable lubrication for gasoline-powered engines. Its universal fit and quart size make it a practical choice to keep engines running smoothly in diverse applications.

Best for: Those who require dependable lubrication to support engine longevity and cleaner operation in gasoline-powered machinery.

Pros:

• Reduces engine wear through strong lubrication in varied conditions
• Helps prevent sludge and deposit accumulation for cleaner engine parts
• Supports emission systems to promote cleaner exhaust output
• Extends oil change intervals for less frequent maintenance
• Performs well across seasonal temperature changes

Cons:

• Some users might find its conventional formula less suitable compared to synthetic alternatives
• Oil additives content can vary slightly between batches

Quick Guide: Best 10W30 Oil For Generator Feature Analysis

Product Name	Viscosity Grade	Vehicle Service Type	Size	Flash Point
Mobil 1 High Mileage Synthetic	10W-30	Car	5 Quart	Not Specified
Shell Rotella T6 Full Synthetic	10W-30	Truck	1 Gallon	480°F
Castrol GTX Conventional Oil	10W-30	Car	5 Quarts	Not Specified
Pennzoil Motor Oil	10W-30	Car, Truck, UTV	1 Quart	Not Specified
Honda Genuine Motor Oil	10W-30	Lawn Mower, Generator, Small Engine	2 Quart	200°C
Maintenance Kohler Synthetic Blend	10W-30	Lawn Mowers, Generators, Small Engines	2 Quart (2 x 1 Qt Bottles)	Not Specified
Honda Power Equipment Oil	10W-30	ATV, UTV	1 Quart	200°C
Valvoline Advanced Full Synthetic	10W-30	Car, Truck	1 Quart	390°F

Which Factors Really Matter When Picking 10W30 Oil for Your Generator?

Choosing oil for generators isn’t just about the right viscosity grade. Several critical factors influence how well your engine performs and lasts under constant strain. Here are the essentials to weigh before making a decision.

Thermal Stability

Thermal stability is all about how well an oil holds up when engine temperatures soar. Generators work hard for hours, so the oil needs to resist breaking down or thinning out under that constant heat.

Take Shell Rotella T6, for instance. It has a 480°F flash point, meaning it doesn’t evaporate or oxidize easily. This comes from its synthetic base oils and a strong additive mix that keeps the oil steady even under tough conditions.

If an oil lacks thermal stability, sludge and thickening can build up. That messes with lubrication and speeds up engine wear—especially if you’re using generic oils not made for heavy, nonstop use.

Wear Protection

Wear protection helps the oil create a tough film that stops metal parts from grinding together during engine use. This is crucial for generators, where constant running can ramp up friction and wear down components faster.

Mobil 1 High Mileage 10W-30 uses a Triple Action Formula that focuses on reducing engine wear, keeping the engine clean, and boosting protection. This formula is designed to shield older or heavily used engines from abrasive damage and keep them running smoother for longer.

Strong wear protection means generators avoid early breakdowns of vital parts like camshafts and bearings. This saves money on repairs and prevents frustrating downtime. Overall, good wear protection extends your generator’s life and reliability, making it a smart choice for heavy-duty use.

Viscosity Control

Viscosity control ensures the oil stays at a consistent thickness despite temperature swings, which is crucial for reliable lubrication. This stability helps the oil flow smoothly, protecting engine parts from wear and tear.

For generators working in different climates or over long periods, a steady 10W-30 grade is key. Honda Genuine 10W30 oil uses shear-stable polymers that resist thinning when hot and thickening when cold, keeping viscosity reliable under heat and stress.

The result is better engine protection, easier startups, and less wear during operation. Oils that don’t control viscosity well can lead to poor lubrication and increased engine strain, especially in cold weather.

Detergent and Deposit Control

Detergents and additives in engine oil work to combat sludge and deposit buildup, which can seriously affect your generator’s performance. Over time, harmful residues develop inside the engine, especially if oil changes are spaced out too long.

Take Valvoline Advanced Full Synthetic 10W-30, for example. It features high-quality detergents that prevent mineral deposits from forming. This reduces friction and keeps your engine running cleaner, smoother, and more efficiently over extended periods.

The result of choosing oil with strong deposit control is a healthier engine. It avoids clogged oil passages and improves heat dissipation, which means less risk of overheating or damage. In short, good detergent action extends your engine’s life and reliability.

Compatibility with Small Engines

Oils designed for small engines like those in lawn mowers, generators, and power tools are made to meet unique demands. These oils use specific additives and base stocks to handle the higher RPMs and materials found in these engines.

For example, Maintenance 2 PK Synthetic Blend and Honda Power Equipment 10W-30 both carry API SM or higher ratings tailored to small engine requirements. This ensures reliable lubrication and protection during operation.

Choosing automotive-only oils can lead to reduced engine protection because their viscosity and additive packages aren’t optimized for the conditions small engines face. Properly matched oil helps extend engine life and maintain performance.

Frequently Asked Questions

Is synthetic 10W30 better for generators than conventional oil?

Synthetic 10W30 oils generally offer enhanced performance for generators due to superior thermal stability and wear protection. Synthetic formulations resist breakdown and maintain consistent viscosity under prolonged high heat, which is common in generator use.

For instance, Mobil 1 and Shell Rotella T6 full synthetic oils contain additives that combat oxidation and sludge buildup more effectively than conventional oils. These features help engines run cleaner and longer.

For optimum generator health, choose a synthetic 10W30 designed for small engines. Avoid conventional oils that may thin out or degrade sooner under constant load.

Can I use automotive 10W30 oil in my generator?

Automotive 10W30 oils can sometimes be used in generators, but they might lack the tailored additives needed for small engine protection. Generators operate differently, often running at steady high RPMs for long durations, which stresses the oil differently than car engines.

Honda Genuine 10W30 and Maintenance synthetic blends are examples formulated specifically for small engines, offering better shear stability and deposit control in these scenarios.

It’s advisable to check your generator manufacturer’s oil recommendations and opt for oils targeting small engine requirements to avoid premature wear or operational issues.

How often should I change 10W30 oil in a generator?

Oil change intervals vary based on operating hours and load but generally fall between 50 to 100 hours of use for generators. Using high-quality synthetic oils might extend intervals closer to the upper limit due to better stability and contamination control.

Some synthetic oils like Mobil 1 High Mileage advertise extended protection, but the actual interval depends on environmental conditions and generator workload.

Regularly check oil condition and follow your generator’s maintenance schedule to avoid running engines on degraded oil that can cause damage.

What does the flash point indicate in 10W30 oils?

The flash point measures the temperature at which the oil vapors ignite, indicating thermal stability and safety margin under high-heat engine environments.

For example, Shell Rotella T6 has a 480°F flash point, showing it withstands higher operating temperatures before volatilizing. Oils with higher flash points tend to resist breakdown and evaporation better.

Select oils with superior flash points to reduce risk of oil degradation during extended runtime, which is common in generator use.

Is high-mileage 10W30 oil suitable for generators?

High mileage 10W30 oils are formulated to address engine wear and deposits typical in older, high-mileage car engines. While they offer advanced additives, their formulation may not be optimized for small engine or generator demands.

Mobil 1 High Mileage offers excellent wear protection, but for generators, oils like Honda Genuine or synthetic blends designed for small engines provide better viscosity stability and thermal resilience under continuous operation.

Stick to oils labeled for small engines or power equipment to ensure compatibility and avoid potential performance issues.

Choosing the Right 10W30 Oil Means Longer Generator Life

The assumption that any 10W30 oil works for generators creates a hidden risk of engine wear and overheating. Selecting oil with thermal stability, wear resistance, and small engine compatibility dramatically improves reliability and performance.

For heavy-duty or high-heat operation, synthetic options like Shell Rotella T6 or Mobil 1 provide excellent protection, while oils like Honda Genuine and Maintenance blends are better tailored for small engines and power equipment.

Applying the correct oil and respecting your generator’s maintenance intervals is vital. Avoid overfilling and ensure proper preheating if operating in cold conditions to prevent viscosity issues and engine damage.

Last update on 2026-01-28 / Affiliate links / Images from Amazon Product Advertising API