Everything expands with heat so that isn’t really a factor
When oil is circulating the level in the pan itself will be much lower and quart in the pan and rest of the engine will not bring the level up to contact the crank
Average car Overfilled 1 qt. anyone ever see this cause a problem?
- Thread starter WobblyElvis
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When oil is circulating the level in the pan itself will be much lower and quart in the pan and rest of the engine will not bring the level up to contact the crank
Yeh, you right Pablo, my bad 
... Sorry Gonna need more than one over to get to the crank 
... Sorry Gonna need more than one over to get to the crank
Don’t get me wrong some are close no need to be sorry. Think of where the windage tray is in some enginesYeh, you right Pablo, my bad
Carlostrece
$100 Site Donor 2025
If overfilled a lot (likely more than 1 qt over)... The crankshaft whipping through the extra oil would reduce gas mileage and power. More concerning, it would also aerate the oil. Aerated oil doesn't pump well and doesn't lubricate well. The extra oil could also cause too high oil pressure that might burst seals or gaskets. Lastly, oil could be forced through PCV and intake ports into combustion chamber.
How many of those problems may occur, and to what extent, depends on how overfilled the oil is, how high rpm gets, and design of specific engine. If only minor overfilling (1 qt or less) then probably little or no issues, especially if driven easy.
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That's why I do my own OC's. Want it done right, do it yourself ( if you have the capabilities ). Never trusted those Jiffy Lube's, Quickie Lube's, or whatever. Case in point : Today / 7-10-25 / drove past a Valvoline Quik Lube joint. Just so happened I was at a red light and turned my head. There they were. 3 guys trying to open a hood on an Audi with a screwdriver. Just hope they didn't dump the oil first.
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I agree with all of this except for the oil pressure because oil pressure is measured at the bearings. I don't understand the correlation between oil level and oil pressure in this example.
Carlostrece
$100 Site Donor 2025
You may be correct. I don't know. What I do know is I saw a 4 quarts overfilled car delevope new leaks that did not exist before. Even after oil level was returned to normal, slow leaks remained.
Also, that same car had blue smoke coming out of tail pipe when overfilled. That would have been either from oil forced up past rings into combustion chamber or oil forced through PCV past intake valve and into combustion chamber.
Why did those things happen? It seems likely to me that increased pressure in crankcase caused those problems. That's what I really meant when I said increased oil pressure. I don't know if oil pressure was increased because that car had no oil pressure guage.
1990 Buick Century in my sig has the Iron Duke 2.5l 4 banger. The sump takes maybe 3.5 quarts max. When my Dad had the car serviced they always overfilled, usually to the amount the 6 cylinder took. This resulted in blowing out the valve cover gaskets and oil running down the front of the block. Proper oil level, a high-end FelPro gasket and about $4.75 in quarters at the local U-wash-it fixed everything.
Toyota overfilled mine by 1 quart twice. I drained it both times but didn’t see any evidence of aeration.
There is a safety factor built in for over -fill. However there is no way to know what and it likely differs by engine.
There is a safety factor built in for over -fill. However there is no way to know what and it likely differs by engine.
There's at least a quart in circulation while the engine is running. Also, I doubt that the specified fill level is touching the crankshaft when the engine is stopped.
With these two assumptions, one quart over shouldn't be a serious problem while the engine is running.
With these two assumptions, one quart over shouldn't be a serious problem while the engine is running.
BrendanC
$100 site donor 2024
if something like my hondas takes 4.75 quarts, it gets a full 5 quarts. only time i do partial quarts is if it is a half quart like 7.5 etc. otherwise below .5 i round down, and above .5 i round up. never had an engine come back or blow up and i wish i could count how many oil changes i’ve done.
OMG !!! The 2.5 liter from the late 70's into the 80's. I used to rebuild them ! Had a fiber type of cam gear directly meshed to the steel crank gear and made that tell tale noise. The stupid cam gear would wear down after awhile, and then the motor would just quit. Distributor/ coil pack in the back of the engine, Real pain to get at. But, aside from that, they were great little engines. My favorite one was in a 1980 Chevy Monza. Wasn't transverse. Super easy to work on. Except I had to raise the engine really high to get that camshaft out. That cam gear was pressed on, so you couldn't do it with the cam in the engine. So, they had a name , " The Iron Duke". Makes sense. An iron lower end with an iron head. NEVER blew a head gasket !!!! Luv'd those little things !!!! Blast from the past !!!! GM put them in everything. Grand Ams, Skylarks, Century's, Cierra's, etc
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Thats what I do with my 2017 Fiesta. Well, I try to hit 4.5 qt. but sometimes it gets 5.
Its 0.5 or 0.7 over, never an issue.
These crazy Russians decided to see (literally) what happens if you overfill engine oil, so they cut the side out of a block, replaced the side with a see-through "window", then fabricated a transparent oil pan. They started testing with the oil at the fill line on the dipstick, then doubled the amount of oil, then tripled it, etc. Each time they would turn over the engine without starting, then ran at idle, then at higher revs.
You'll have to watch to see what happens, but I was very entertained.
You'll have to watch to see what happens, but I was very entertained.
I would rather be over one quart than under one quart.
After an OC, try to clean the dipstick with a clean rag or clean shop towel. A dirty rag can leave a greasy/ oily residue on the stick, making it harder to get a good reading on the level.
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Given the audience here, I doubt many reading this would use a dirty rag.
But it's good advice. Maybe worthy of a clean rag v. rolled shop towel thread.
Hey Pablo .....I've used plenty of semi-dirty rags.....then I smartened up LOL......Only took me like 10 yrs.... You know how it goes, you try to find that one little clean area on a rag, because you're too lazy to go get a new one.....LOL
.....I've used plenty of semi-dirty rags.....then I smartened up LOL......Only took me like 10 yrs.... You know how it goes, you try to find that one little clean area on a rag, because you're too lazy to go get a new one.....LOLI use white Costco paper towel. Is that ok?
I hope very tiny amounts of lint won't hurt the engine. Engines are made cheap these days and lint from the paper towel may reduce the clearances due to ever so decreasing lint tolerances in these cheap engines! I was told thicker oil does a better job dissolving the lint.
I hope very tiny amounts of lint won't hurt the engine. Engines are made cheap these days and lint from the paper towel may reduce the clearances due to ever so decreasing lint tolerances in these cheap engines! I was told thicker oil does a better job dissolving the lint.
Only if you're running a filter having media made of cellulose. Otherwise, you risk cross-contamination.
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