Interesting Oil Change

[olddog]

Originally Posted by jhv48

Glad somebody finally brought this up.

I have a nine quart pan and remote oil filter and cooler. It takes 10 quarts of oil to completely fill the engine, filter and cooler when dry. The dipstick is at full, and when I drain the oil, I get 7 quarts out. Now, when I fill it back up, it takes the full 9 1/2 quarts to fill the pan and filter. WTF!

The oil level on the dipstick is exactly where it was before the oil change. So how come I only get 7 quarts out of the engine (including the oil in the filter) and it takes 9 1/2 quarts to fill it back to the full level in the dipstick?

What am I missing? Does it every time!

If you take 7 quarts out of a bucket and pour 9.5 quarts back in and repeat, eventually the bucket is going to run over.

1) You do not get all the oil out of the filter, so you are not measuring all the oil that comes out. But that does not explain 2.5 quarts.

So after pouring the oil in, you start the engine to fill the filters and then measure. Do you start the engine prior to draining and check the oil apples to apples? I suspect the engine has sat and more oil has drained into the pan, so it measures full, but there is less oil in it than there is after you refill it. Which means that 2.5 quarts minus what you don't get out of the oil filter and drain pan, when you measure what came out, is getting burned or leaked by your engine.

You absolutely cannot put more in than you drain out, without an equal amount leaving the system in some other way, or it will overflow.