On my wife's 2001 Forester, I had to have the head gasket replaced on one side. The mechanic, whom we consider to be competent, based on our previous experience, overfilled it when he replaced the oil. Should I be concerned?
-- Charles Packer
Yes, depending on How much?
I dunno if anyone can say precisely at what point it could be a problem. I personally would probably allow 1/2 or slightly more quart overfill. The issues, supposedly , are; the crankshaft could beat the oil to a foam, compromising the pumps ability to move the oil. Might be problems with excess oil being pushed out thru the crankcase ventilation system too I guess.
Doesn't it also raise the oil pressure?
I doubt it would affect the oil pressure relief valve. i suppose it's 'possible' - but I don't know what the mechanism would be to cause that.
Why in the world would it do that?
Actually, that's the story I heard somewhere -- that overfill of oil would "blow your seals"...but if there's a pressure relief valve, then the engineers have thought of that too, haven't they? In this case the oil has been so overfilled that no amount of wiping off the dipstick and reinserting it shows where it was filled to. The radiator reservoir was overfilled also. Sigh... this is why I'm happy to do the regular oil changes of our cars myself.
-- Charles Packer
I had bad luck with the cheapo siphon I tried years ago - but there ARE devices that will let you pump the oil out of the dipstick tube, some of them attach to a drill motor I think. Might be a little easier if you could borrow/rent one. Otherwise, you're gonna have to pull the drain plug. It can be tricky sometimes to get a reading on my soob's dipsticks. Just triple check before getting crazy!
Overfilling will not raise the oil pressure from the oil pump. That pressure is limited by the oil pressure relief valve. It would probably lower the oil pressure if the oil turns to froth from direct contact between the crankshaft and the oil level in the pan.
Overfilling might blow oil seals or pan gaskets and valve cover gaskets due to increasing the pressure in the crankcase from whipping the oil into a froth from contact with the crankshaft. The reduced air space in the crankcase due to overfilling would contribute to the crankcase pressure increase.
If it seems OK after dra> > > > Doesn't it also raise the oil pressure?
On that note, I called the shop and told the manager that somebody there had overfilled the oil. He agreed it could be "bad" and told me to bring the car by to have it corrected. Stay tuned.
-- Charles Packer
The folks at the shop told my wife it was about a half-quart overfilled. Whatever. It had looked like a lot more to me. At any rate, they corrected it.
-- Charles Packer
I THINK most oil change shops have a central pump and the fill nozzle has a dial selector. It may not be able to adjust accurately or in half-quarts so maybe they err on the side of a slight overfill?
anyway - glad it got corrected.
Carl
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