This got brought up at breakfast today with a friend of mine.

A few years back I took my Type R to the local Acura dealer for a few things to get done before my trip from Ohio to Road Atlanta. One of the things they did was an oil change. The next day as I was getting ready to leave for RA, I checked the oil and it was above the full line, probably 1/4". I didn't have time to mess with it so I swung by the dealer and had them drain some out. The service guy said that it wouldn't hurt anything, but since I was going to be doing some hard driving I didnt want to take any chances.

Could this have caused a problem? Or was the service guy correct? Just curious. At breakfast my friend said that it wouldn't hurt anything, but like I mentioned, I didn't want to take any chances.


[Modified by Brett@SoloRacer.com, 8:29 AM 3/14/2003]

 

I always run a 1/2 qt over in the race car. Since I run 5W30 RedLine, the motor will use a some oil on track, plus I almost never see revs below 6000, all the oil is up in the head and it is good to have some extra. By the end of a typical day, the 1/2 qt is gone and it is "full". I will then add some more the following morning. Not sure if there are any bad side effects for street driving at low(er) RPMs.

 

It won't hurt. I slightly overfill. I burn 3/4 to 1 quart of Redline for every 90 minutes on the track.

Warren

 

If your car is a race car (ie you have a catch can) the over spill of oil will get dumped into the catch can. We do this all the time for a formula vee, (old bug motors). If you have no catch can, the excess oil will be injected into the throttle body and burned out as oil smoke.

I heard over filling with oil can foul the plugs, but I only heard that. I can be wrong.

 

I overfill by 1/2 a quart and have never had problems.

 

Supposedly, if you overfill by a lot (probably a quart or more over), you can damage seals such as the front or rear mains. I've never seen it happen... but I've read that it can.

 

More oil in the system = more oil pressure than normal

Less oil in the system = less oil pressure than normal

 

Some cars don't like to be overfilled - the crank catches the oil and makes it frothy. This would normally be 1qt+ over full. My race car is always about 1qt over the full line, but there is no crank to froth the oil up.

 

How does having more oil in the car than is specified increase oil pressure? Certainly, low oil levels might lead to starvation at the pump, but I don't see how having more oil sitting above the pickup would increase the pressure of the system.
-Adam

 

I have to run about 3/4 to 1 qt extra of oil in the prelude.. It likes to cut off high cam in transitional corners.. So, about 6qts total...

 

The oil pump does not change it's output with a increase/decrease of oil in the pan.

 

Ok, I guess I'm wrong on this but I always thought that the oil pressure indication was showing 'block pressure' in a closed system. I was reasoning that an increase in the volume of oil in the system would raise the pressure since air volume would have been decreased. Maybe I should actually read up on how the oiling system of modern engines work...

 

the vent off of the valve cover = vent to the crankcase

 

I was told it was good to overfill in transversly mounted and V configuration motors when driving on track because the oil sloshes to one side or the other and could prevent the other side from getting all the oil it needs. I guess it would depend on the engine on how much to overfill.

 

Sloshing is caused by crappy stock oil pans that don't have baffles to reduce said sloshing. Road race pans have lots of baffles (like a waffle pattern) to keep the oil more stable.

 

well, i'm no expert, but i'm with the more oil = more oil pressure. i base this not only on a greater volume of oil, but also the difference between oil and air at ambient temp compared to oil and air at operating temp. i have also heard that overfilling can cause leaks in the seals cuz of this overpressure. never thought of the crank making oil frothy, but i could see it happening, as well as more oil to slow down the crank which i dont think would be too significant, but still a variable in this equation. i figure you cant go wrong if you keep the levels within the recommended specs so long as you check it often and add when necessary.

-brian "who puts mobil1 on his cereal"

 

The extra volume of oil is just going to sit in the oil pan at the bottom of the crankcase - not be forced up into the oil galleys where more volume would generate higher pressures. This is a function of your oil pump.

 

Too little oil = pump starvation = no lubrication = bad
Too much oil = crankshaft sloshing = frothing = air bubbles = no pressure = no lube = bad

There's a certain amount of oil which works well and neither starves nor froths. So just like someone said - check often especially when you drive hard. H22's have a habbit of burning oil, so constant top-ups are likely. Oil volume has nothing to do with oil pressure as long as you're neither starving nor frothing it. The crankcase IS ventilated after all (PCV valve!), so you're not going to build up any kind of air pressure in there to pressurize the oil.