Engine and gear oil levels

[Can Can]

I actually have 3.73s, and the reason I said a third is because you're probably running at 60% or less capacity when you're up to your kness in water.

Anyhow, I'm not disputing the fact that too much oil is bad. I would prefer, however, to hear a little of the science behind it, not just "too much is bad because it hits the crankshaft and slows you down". There has to be more to it.

 

[zeroz400]

I'm kind of thinking of those cheesy lucas oil displays you see at the auto parts store counters ...the gears pick up the lube and hold onto it as they mesh, (visualizing ring/pinion here) so a) what advantage is there to overfilling, b) if the gear oil froths up, will it be as effective once the gears mesh, c) will the lube be picked up by the gears as easily, and d) isn't overfilling wasting power?

http://www.bobistheoilguy.com/images/lucas/lucas.htm Check that out.

 

[DEMON44]

It's not the drag thats the problem...........it's the fact that when the crank throw hits the oil it whips it into a froth = bubbles = air............air in the oil does not lubricate. When it hits the pickup tube and the oil pump full of little bubbles it goes directly to your main bearings = metal to metal contact.

Thats the Coles Notes version of the problem with overfilling your oil pan............ yes race car guys have different veiws on HP robbing properties. Like putting a windage tray on so oil doesn't "splash" the crank and slow it down. not so they can run the crank through the oil. and a vaccume pump on the crank case, so theres no air pressure to slow the crank down.

 

[rumbly truck]

I think it was hot rod magazine, with Jeff Smith writing, that tested oil levels with a moroso deep pan against power levels.If I remember right, 1 quart low was the winning number. When you get into windage, you work several factors against the engine. When your splashing that much oil around in the crankcase, it can load up the liner walls to the point of overloading the oil rings. Then it can get into the combustion chambers, and either just burn, increasing oil comsumption , or cause detonation.Next, the increase in flight time of the oil dont allow for heat transfer of the oil droplets into the main sump oil body.Yes it will heat the oil up. Then you emulsify air into the oil by the taffy making machine you have in a rotating assembly.This gets you two ways, now you have foaming oil that you are trying to pressurize to feed the bearings. To bad the foamed oil will now compress. Then you have the foamy oil that tries to lube , clean, and pull away heat. Just like any weak link in the chain, the foamy oil will not pull away the heat like good oil will. Damaging both the oil, and hard parts. But that said, the angles some of these engines get run isn't good.I would rather have a high crankcase level. than no oil at all getting to the engine.

 

[rumbly truck]

The drag racers use the vaccum pump , so that they can use low tension ring sets to lower rotational forces. Then the vaccum pump puts a negative pressure in the crankcase helping the rings seal.

 

[dyeager535]

Yeah, I'd seen that before, only statement in there that applies is about the antifoaming properties of the lube, which I expected to be present. But thats the sort of gear setup I was referencing. Oil climbs great, but I certainly can't spin it like that guy could, and as was mentioned, that is a different setup than an axle assembly.

Still, pretty hard to figure out if overfilling the diff is going to hurt things, or even allow the stuff to foam a bit. Guess someone has to get a clear diff cover and try it lol.

Overfilling oil to a certain extent in a "street" vehicle probably hurts nothing. But when you start nose up or nose down, all that extra oil is puddling up in that direction, which will put it directly into the crank. Not to mention many of the racing articles are probably either dealing with straight line forward acceleration (oil to the back) or circle track. (oil all to one side, all the time)

Really not much point to running extra engine or (stock diff angle) gear oil that I can see, if the oil is getting too hot, run a cooler, if it leaks, fix the leak.