Q: What Oil Viscosity Should I Use With My Filter?

Oil is the life’s blood of every engine. It lubricates the internals of your engine, it cools your engine, and it keeps your engine clean.

Oil viscosity, or the measurement of an oil’s resistance to flow, is a key property of the oil we use in our cars. There are many different viscosities of oil that are available. The most common oil viscosities are 20W-50, 15W-40, 10W-40, 10W-30, 5W-30, 5W-20, and 0W-20.

The oil in your engine must be thick enough to protect the internal components of your engine, but not too thick. Oil that is too thick flows slowly and is not capable of protecting your engine.

Engines have, in the past, used 10W-30 oil as the primary grade of oil. More powerful engines typically use 20W-50 or higher because of the additional stresses that those engines are subjected to.

Many engines today use lighter oils like 5W-30 or even 0W-30 because of the tighter tolerances that they’re built with. Tighter tolerances translate to smaller paths for the oil to flow.

Diesel engines most commonly use 15W-40 or 10W-30, depending on ambient temperatures. One quick way to check which viscosity oil to use in your car is to look at the oil fill cap on your engine. It should have the oil viscosity that is recommended by your vehicle’s manufacturer. If you need help with an oil change, a technician from YourMechanic can come to your home or office and perform this task at your convenience.