Does motor oil expire? If not, how long does motor oil generally last?

Motor oils do not have documented expiration dates. When stored under optimal conditions, the product remains stable for an extended period of time. It can be used as long as the American Petroleum Institute (API) rating on the label continues to meet or exceed the requirements listed in your car’s owner's manual. If the rating is still current, we advise you shake the container before use to blend any additives that may have settled.

Does motor oil ever wear out or does it just get dirty?

Yes, motor oil does break down. Oil additives are consumed and combustion byproducts build up in the oil. Changing your motor oil on a consistent basis removes combustion byproducts and replenishes the additives.

Does my vehicle's oil filter need to be changed with every oil change?

Phifa recommends you replace the oil filter with every oil change, as this will eliminate any risk of contaminants trapped in the oil filter (e.g., dirt) from re-entering the new oil. Always be sure to follow the oil change frequency recommendations in your vehicle’s owner’s manual and to use an oil filter meeting automotive manufacturers’ guidelines: e.g., USCAR. - 

Are conventional motor oils natural, unprocessed products?

The base oils used in conventional motor oils do come from petroleum, but they have gone through extensive refining processes. These base oils are compounded with various additives, which provide important properties such as antiwear, friction reduction and long life.

Why do some motor oils carry the "API Certified - For Gasoline Engines" starburst symbol on the bottle while others do not?

The starburst symbol means that the oil meets the requirements of the International Lubricants Specification Advisory Committee (ILSAC) in addition to the requirements of API, as stated in the API starburst symbol on the back of the bottle. Only certain viscosity grades are eligible for the starburst symbol.

Can motor oil significantly improve horsepower?

Yes. Motor oil formulas with friction modifiers and additives help to improve horsepower. Lower viscosity (lighter) oils can improve horsepower providing that they separate moving parts and maintain engine durability. The optimum oil viscosity for a given engine is specified by the automotive manufacturer.

Is it a good idea to let your car warm up (idle)?

Most modern cars don’t require idling time before driving.

What does the "w" in a grade of motor oil stand for?

The "w" in motor oil stands for winter. The first number in the oil classification refers to a cold weather viscosity. The lower this number is, the less viscous your oil will be at low temperatures. For example, a 5W- motor oil will flow better at lower temperatures than a 15W- motor oil. The higher number, following the “w” refers to hot weather viscosity, or how fluid your oil is at hot temperatures. The higher the number, the thicker the oil at a specified temperature.

Is thicker oil better?

In some circumstances, thicker oil can be used to compensate for increased bearing clearances (gaps between bearing and rotating shaft) that have developed over the years. A large change in bearing clearances can result in poorer lubrication. For best performance always follow the recommendations for motor oil viscosity in your vehicle's owner's manual.

When does it make sense to use straight weight oil (SAE30) versus a multigrade oil (5W-30)?

Straight weight oil is never recommended for use in a system that requires a multi-viscosity oil. Straight weight oils are generally recommended for smaller engines or older vehicles that were made before multi-viscosity oils were produced.