Where to look it up
- The owner’s manual — usually under “specifications” or “recommended fluids”. Many manuals are free on the manufacturer’s website.
- The oil filler cap — many engines have the viscosity printed on it.
- A parts store or dealer — they can look it up by year, make, model and engine, or by VIN.
Viscosity: the 0W-20 part
The two numbers describe how the oil flows when cold (the number before the “W”) and at running temperature (the number after it). Modern engines are designed around a particular grade, so use the one listed. Our 0W-20 vs 5W-30 guide explains the numbers in plain language.
Specifications: the part people miss
The grade alone isn’t enough. The manual also names a standard the oil must meet — for example an API or ILSAC rating, or a manufacturer’s own approval such as GM’s dexos or approvals from European brands. The approval is printed on the oil bottle. Using oil without the required approval can matter for engine protection and warranty claims.
Synthetic, blend or conventional?
Many modern engines require full synthetic oil; others allow any oil that meets the specification. See synthetic vs conventional oil for the differences.
Common questions
Can I use a different grade in an emergency?
Topping up with a different grade to get you home is generally better than running low. Get back to the correct oil at the next change.
Does the brand matter?
Less than the grade and specification. Any oil that carries the required approval meets the standard your manufacturer set.
How much oil does my car hold?
The manual lists the capacity with a filter change. Add slightly less, check the dipstick, and top up to the full mark — see how to check your oil.