Using high-quality motor oil is essential to engine performance and longevity. AMSOIL® synthetic motor oils are engineered to consistently outperform conventional oils and many other synthetic brands across a wide range of critical performance areas. These include wear protection, high- and low-temperature performance, viscosity stability, foam control, rust and corrosion resistance, volatility control, and fuel efficiency. While some motor oils may excel in one or two of these categories, AMSOIL synthetic motor oils are designed to deliver top-tier performance in every area. This balanced, high-performance formulation gives drivers confidence that their engines are receiving maximum protection under all operating conditions. AMSOIL synthetic motor oils are formulated with premium synthetic base oils and advanced additive technology to support extended drain intervals and superior engine cleanliness. Their robust Total Base Number (TBN) retention helps neutralize harmful acids and resist oxidation, which are common causes of oil breakdown. In addition, AMSOIL oils exhibit exceptional resistance to high-temperature volatility, helping reduce oil consumption while maintaining proper viscosity for longer service life compared to many other oils. For specific performance claims and drain interval recommendations, always refer to the applicable product data sheet.

Yes. AMSOIL synthetic motor oils are compatible with other conventional and synthetic motor oils. Mixing other oils with AMSOIL motor oils, however, will shorten the oil’s life expectancy and reduce its performance benefits. In some cases, mixing AMSOIL lubricants will not cause immediate failure but will reduce performance. For example, AMSOIL Signature Series 5W-30 and AMSOIL OE Synthetic 5W-30 Motor Oil share similar chemistry and can be safely mixed in an emergency top-off situation. However, doing so will reduce the performance benefits and shorten the service life of the Signature Series oil. For this reason, AMSOIL does not support extended drain intervals when oils have been mixed. To ensure optimal performance, reliability, and warranty protection, AMSOIL recommends using the correct lubricant for the application and avoiding mixing products whenever possible. AMSOIL does not support extended drain intervals where oils have been mixed. Mixing other oils with AMSOIL motor oils will also void the AMSOIL limited warranty.

Yes — you can mix 0W-20 with 5W-30 motor oil, but it should be treated as a temporary solution, not a best practice. Here’s what to know: It won’t cause immediate harm. In an emergency or for a short-term top-off, mixing these oils is generally safe. The viscosity will be altered. The blended oil will fall somewhere between a 20- and 30-weight at operating temperature and won’t match either specification exactly. Cold-start and fuel-economy benefits may be reduced. Engines designed for 0W-20 rely on its low viscosity for fast oil flow and efficiency, especially during cold starts. Not recommended for long-term use. Running a mixed viscosity long term can reduce performance, protection, and may raise warranty concerns. Bottom line: Mixing 0W-20 and 5W-30 is acceptable only as a short-term or emergency measure. For optimal engine protection and manufacturer compliance, return to the specified oil grade at the next oil change. To ensure optimal performance, reliability, and warranty protection, AMSOIL recommends using the correct lubricant for the application and avoiding mixing products whenever possible.

AMSOIL does not recommend mixing AMSOIL synthetic lubricants. AMSOIL lubricants are engineered with specific performance properties to meet the exact demands of their intended applications. Each product is carefully formulated under strict quality control standards to deliver maximum protection and performance. Because of this, mixing AMSOIL lubricants is generally unnecessary and can result in reduced performance or, in some cases, equipment damage. Automatic transmission fluids illustrate this clearly. Different transmissions require fluids with specific friction characteristics to ensure proper clutch engagement. Mixing fluids designed for different specifications can cause issues such as erratic shifting, clutch slippage, or even transmission failure. In some cases, mixing AMSOIL lubricants will not cause immediate failure but will reduce performance. For example, AMSOIL Signature Series 5W-30 and AMSOIL OE Synthetic 5W-30 Motor Oil share similar chemistry and can be safely mixed in an emergency top-off situation. However, doing so will reduce the performance benefits and shorten the service life of the Signature Series oil. For this reason, AMSOIL does not support extended drain intervals when oils have been mixed. To ensure optimal performance, reliability, and warranty protection, AMSOIL recommends using the correct lubricant for the application and avoiding mixing products whenever possible.

While viscosity is an important part of motor oil selection, it is only one factor in overall oil performance. A significant portion of an oil’s performance and compatibility comes from its additive package. AMSOIL offers multiple oils with the same viscosity because each product is formulated with a unique additive system designed to meet specific manufacturer requirements and industry specifications. Different engines and equipment manufacturers require oils that meet particular performance standards, such as wear protection, deposit control, fuel economy, or emission-system compatibility. By offering multiple formulations within the same viscosity grade, AMSOIL is able to provide premium oils that meet a wider range of OEM specifications and application needs than would be possible with a single, one-size-fits-all oil. This approach ensures customers can select an AMSOIL oil that not only has the correct viscosity, but also delivers the exact performance and protection required for their specific engine or equipment.

There are no special requirements for changing to AMSOIL synthetic motor oil. However, in older vehicles with high mileage, it may be advisable to use AMSOIL Engine and Transmission Flush first. This will ensure the engine is clean and free of accumulated contaminants that may affect the service life of AMSOIL synthetic motor oil. Installation of an AMSOIL Oil Filter at every oil change is also recommended.

Because cold-temperature storage can be detrimental to the performance of some AMSOIL products, AMSOIL offers the following storage recommendations: Lubricants: Store at temperatures at least 10°F above the lubricant's pour point. Greases: Store in a dry environment at temperatures above freezing (32°F). Gasoline Additives, Engine and Transmission Flush: No adverse issues with cold-temperature storage. Diesel Injector Clean, Diesel Cetane Boost, Diesel Recovery: No adverse issues with cold-temperature storage. Diesel Cold Flow: Store at temperatures above 0°F. Brake Fluids: Do not store at temperatures below -40°F for longer than two weeks. Heavy Duty Metal Protector, Metal Protector, Power Foam, Fogging Oil, Chain Lube, Brake and Parts Cleaner, Firearm Cleaner, Silicone Spray, Spray Grease, Heavy-Duty Degreaser: No adverse issues with cold-temperature storage as long as products are allowed to warm to room temperature before use. Miracle Wash®: Store at temperatures above freezing (32°F). Antifreeze and Engine Coolant: Will not freeze. No adverse issues with cold-temperature storage. Coolant Boost: Store above 32°F. Slip Lock®: No adverse issues with cold-temperature storage. If product separates, heat to room temperature and shake well before use.