When I changed my oil last I was just above the Full mark, 5000km later I'm at the Low mark. I won't have time to change the oil until next week so I topped it up.

My question is how do you know how much to top up? what is the actual volume difference between L and F?

If this is vehicle specific it is a 2008 WRX using Motul 8100 5w-30.

1 Answer 1


It is very definitely vehicle specific. Every manufacturer is going to or can do it differently, and they do. Think of how many liters your Subie holds for a fresh oil change and for that in a semi-truck. We are talking the difference of quarts to gallons in total.

To answer your question, this is basically a trial and error way to do business. You put an "amount" into the crankcase and check the dipstick for the level. If too low, add a bit more. You ultimately get used to how much is needed in your specific vehicle by your past experience.

If I were a guessing man, I'd probably put the difference between the high/low marks at ~1/2 liter (or quart ... depending on your local) in most non-commercial vehicles. That is what experience has shown me, anyway.

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