As noted here (I think) and in the “Engineering Toolbox”, oil volume expands with increasing temperature. And if I’m interpreting the “Toolbox” graphs correctly the increase is of some significance: from room temperature to 100C on the order of 5-6%.
So when we buy a 5-quart jug of oil, at what temperature do we think the oil volume is based? An oil’s PDS will generally show a density factor (presumably vs water) at about 15C, or roughly room temperature. Is it reasonable to assume this is 5-quart volume temperature at which an oil is bottled?
If this is so, let‘s assume we change the oil with the specified amount and the following morning, when the sump has cooled, add a bit more to bring the dipstick to the “full” mark. If we then take a long Interstate run and check the oil does seem reasonable to assume the oil level will be 5-6% higher than when cold? I realize this isn’t much, but on a 5-quart sump it’s still and extra 1/4 quart which should be noticeable. Does anyone see this?
And does this suggest that filling a cold sump to absolutely full is not necessarily the best approach? Maybe using the specified amount and being content if the result is a bit short of full is better?
I realize we’re kind of in the weeds here, but with some discussion about fuel dilution and rising sump levels I wonder if this could be a factor.
Thanks.
So when we buy a 5-quart jug of oil, at what temperature do we think the oil volume is based? An oil’s PDS will generally show a density factor (presumably vs water) at about 15C, or roughly room temperature. Is it reasonable to assume this is 5-quart volume temperature at which an oil is bottled?
If this is so, let‘s assume we change the oil with the specified amount and the following morning, when the sump has cooled, add a bit more to bring the dipstick to the “full” mark. If we then take a long Interstate run and check the oil does seem reasonable to assume the oil level will be 5-6% higher than when cold? I realize this isn’t much, but on a 5-quart sump it’s still and extra 1/4 quart which should be noticeable. Does anyone see this?
And does this suggest that filling a cold sump to absolutely full is not necessarily the best approach? Maybe using the specified amount and being content if the result is a bit short of full is better?
I realize we’re kind of in the weeds here, but with some discussion about fuel dilution and rising sump levels I wonder if this could be a factor.
Thanks.