Can AMSOIL motor oils be mixed with other brands?
Answer: Yes. AMSOIL motor oils can be mixed with other motor oil brands; however, mixing AMSOIL products with other brands may decrease the effectiveness of AMSOIL oils and compromise their extended drain capability. Mixing other oils with AMSOIL motor oils also may void the AMSOIL limited warranty.
Will synthetic motor oils cause engines to leak oil?
Answer: No. Synthetic oils do not cause engines to leak oil. In fact, AMSOIL motor oil is fully compatible with modern seal materials and is properly formulated to condition seals, keeping them pliable to prevent leakage.
Can synthetic oil be used in new engines?
Answer: Yes. Synthetic oil is perfectly safe for use in new or high-mileage engines.
Must new cars be broken in using petroleum oil?
Answer: No. AMSOIL Synthetic motor oils are safe to use during break-in. In fact, many vehicles – including the Dodge Viper and Chevrolet Corvette – are factory filled with synthetic oil.
Is there a recommended procedure for changing to AMSOIL motor oil?
Answer: There are no special requirements for changing to AMSOIL motor oil. However, in older vehicles with high mileage, it may be advisable to use AMSOIL Engine Flush first. This will ensure the engine is clean and free of accumulated contaminants which may affect on the service life of AMSOIL motor oil. It is recommended that an AMSOIL Absolute Efficiency Oil Filter (EaO) be installed at every oil change.
Why are AMSOIL engine oils capable of extended drain intervals?
Answer: AMSOIL engine oils are formulated using premium synthetic base oils, and the highest quality additives, that provide extended-drain capabilities. Formulated with high quality additives, AMSOIL engine oils achieve greater cleaning powers, while providing better equipment protection over longer oil drain intervals. AMSOIL’s unique synthetic formulation, and robust TBN retention, works to resist oxidation and neutralize the acids that shorten the service life of other oils. AMSOIL’s strong resistance to high temperature volatility (burn-off) helps reduce oil consumption, while maintaining viscosity over longer periods of time than other oils. Please check the product data sheet for specific recommendations.
How do AMSOIL motor oils compare to other motor oils?
Answer: The importance of good-quality oil in your engine cannot be stressed enough. AMSOIL synthetic motor oils consistently outperform other conventional and synthetic oils in virtually every category of performance, including wear protection, extreme high and low temperature performance, foam control, viscosity retention, rust and corrosion protection, volatility and fuel economy. While other brands may have good performance in a few of these areas, AMSOIL consistently performs at the top in every category. Drivers can have confidence knowing that AMSOIL motor oils provide maximum performance and protection.
What are “normal” and “severe” driving conditions?

Answer: Each vehicle manufacturer defines “normal” and “severe” driving conditions for their equipment; AMSOIL recommends owners check these definitions in their owner’s manual to determine the service condition in which they typically drive.

AMSOIL defines normal service as personal vehicles frequently traveling greater than 10 miles at a time and not operating under severe service.

AMSOIL defines severe service for gasoline engines as turbo/supercharge engines, commercial or fleet vehicles, excessive engine idling, use of AMSOIL engine oil in vehicles with more than 100,000 miles without prior regular use of AMSOIL engine oil, daily short-trip driving less than 10 miles (16km), frequent towing, plowing, hauling or dusty-condition driving.

AMSOIL defines severe service for diesel engines as extensive engine idling, daily short-trip driving less than 10 miles (16km) or frequent dusty-condition driving.

Source: amsoil.com