oil overfilled?

[thestick]

Had the oil in my 2001 Forester changed at the dealer today. I brought
4qts with me. The tech said it took 4.7 and I would be stating almost a
qt low. I said the manual says 4.2 and that I would add the .2 later.
He insisted he was right so I let him add the extra.

Later, I checked the level and found it to be 1/4 inch over the full
mark on the dipstick. Should I remove the excess? Will it do any
damage as is?
thanks
g

 

[Edward Hayes]

The correct fill is 4.2 quarts and that brings me to the full hole.
Your not over filled if when the oil is checked HOT that it is NOT
over the notch above the full hole. Ed

 

[l.lichtman]

But, part of the question remains unanswered: will overfilling the oil
sump harm the engine? I don't think so, but I am willing to be
corrected. As far as I know, the extra oil may be dissipated, somehow,
but I don't see how it could harm anything, except, maybe, the
environment.

 

[Carl 1 Lucky Texan]

The story in the old days was that, if the level were high enough to be
'beat into foam' by the crankshaft the oil pump wouldn't be able to pump
the foam and you'd have oil starvation. I suspect with newer oil
formulations and having the pickup for the oil low in the sump, it might
be difficult nowadays to get into that kinda trouble - not impossible -
just unlikely if you're slightly overfilled.

Carl

 

[Rick Courtright]

Later, I checked the level and found it to be 1/4 inch over the full
mark on the dipstick. Should I remove the excess? Will it do any

Hi,

Is that hot or cold? If hot, it sounds "just about perfect" (see Ed's
description of "hot" mark) and if it's cold, it's a tiny bit overfilled,
but not enough to worry about (see Carl's description of foaming--still
potentially as much a problem as it ever was if grossly overfilled, but
your description doesn't raise any red flags.) Overfilling by the
dealers seems to be a common thing--I always do my own oil changes to
maintain control over all aspects: brand, weight, amount, but looking
thru the service records of my Toyota which was dealer maintained
exclusively prior to its coming to live at my house, sometimes an oil
change was charged by the quart, often at 5 qts in a 4.5 qt engine (did
they keep a half qt, or just pour it in?), other times it was "one unit,
6 cyl" so they probably just dialed a figure on the dispensing hose and
let 'er rip. Regardless, that car's at 227k miles right now with no
known adverse effects. So I wouldn't worry about the Subie...

Rick

 

[Michael]

I did this when i changed the oil in my wrx. My issue was the car was not
perfectly level when i changed it. So i added more. I had about that.. 1/4
over the full line ,i did drain mine down. To much oil can cause excess
pressure in the crankcase. Damage gaskets and seals and cause leaks. Like
the rear main seal, oil pan gaskets. And if its way to high the crankshaft
will be turning in the oil and that will cause more load on the engine, poor
milage and pre-mature wear.

 

[remco]

I did this when i changed the oil in my wrx. My issue was the car was not

perfectly level when i changed it. So i added more. I had about that.. 1/4
over the full line ,i did drain mine down. To much oil can cause excess
pressure in the crankcase. Damage gaskets and seals and cause leaks. Like
the rear main seal, oil pan gaskets. And if its way to high the crankshaft
will be turning in the oil and that will cause more load on the engine, poor
milage and pre-mature wear.

Totally agree -- the extra pressure may not do damage you notice right now
but in the future.
I woulnd't take the risk - draining some of the oil is easy.

 

[Rick Courtright]

over the full line ,i did drain mine down. To much oil can cause excess
pressure in the crankcase. Damage gaskets and seals and cause leaks. Like
the rear main seal, oil pan gaskets. And if its way to high the crankshaft
will be turning in the oil and that will cause more load on the engine, poor
milage and pre-mature wear.

Michael,

I hate to be skeptical, but I've been spinning wrenches for a LOT of
years (scary close to a half century), and nobody's ever been able to
prove this "too much pressure" thing to me: the oil pump doesn't create
more oil pressure just cuz there's a bit more oil, and any air pressure
buildup is taken off by the PCV system (or the old road draft system for
those who've been around long enough to remember.) The engine's
crankcase is NOT a sealed system with no pressure relief designed in. If
it were, your engine would probably last about 15 minutes before
self-destruction. Methinks that "excess pressure" thing's an old wive's
tale that needs to be put to rest.

And the crank turning in the oil isn't going to cause enough drag to
make a difference. What CAN happen (assuming the oil level's grossly
overfilled, which a quarter or even half quart in a car engine's NOT
gonna be) is that the crank will churn the oil, causing foaming. "Foamy"
oil doesn't lubricate well, causing lowered oil pressure and a lack of
lubrication at critical points, including seals, which CAN cause the
seal damage and engine wear you mentioned.

Maybe you can elaborate on what I've missed? I'm willing to learn
something new.

Rick

 

[thestick]

I checked it again this morning. It's about half way between the cold
full hole and the hot full notch.
So I guess I'll leave it as is.
thanks
g

Rick Courtright wrote:

 

[Edward Hayes]

Your just fine. If like I said it's not over the notch when hot then
Subaru says good.

 

[CompUser]

Totally agree -- the extra pressure may not do damage you notice right now
but in the future.
I woulnd't take the risk - draining some of the oil is easy.

Yup.

First wife blew the diaphragm in the oil send
unit, by overfilling by less than a quart, on one
of my cars.

I've never seen a baby born, but I'd be a fool to
claim that proves it never happens ;-)

 

[Michael]

Maybe this makes sense.. if there is to much oil in the crankcase it takes
up more space, leaving less space for the air. Same ammount of air being
forced in a smaller space will make more pressure. The pvc, old breather
system can only relieve so much. I rebuilt a chevy 327 and a Ford 302. The
327 was out of a 69 impala i put in a 71 nova. The 302 was a 72 in a Bronco.
I remember a few times while working on them having the breathers blow out
of the valve cover and the dipstick pop out.This has nothing to do with to
much oil but to much pressure built up from turning it over alot and it
couldn't relive it. So the system pcv is ok under normal conditions,but to
much oil, to much pressure it cant relieve properly and could blow out
seals, gaskets. The extra pressure has to go somewhere. And if you get in a
pool and try to walk, how much more effort do you use then out of the water
? Any extra load on the rotating assembly will affect milage, wear and
performance.

 

[jabario]

I think the whole point is "how overfilled"? Four ounces will make no
difference. Do you keep exact track of how much oil isremoved? If not
you may overfill. Four quarts probably will!!! Why are some of you so
anal? Will the roof rack fail w 101 lbs?

 

[Rick Courtright]

Maybe this makes sense.. if there is to much oil in the crankcase it takes
up more space, leaving less space for the air. Same ammount of air being

Yes, I understand the concept. But did you blow things out of your
engines cuz you overfilled them with oil? And if so, how far were you
overfilled?

I've seen the same thing happen you've described, but there was a much
more serious problem than a little too much oil! (And with all due
respect to home garage builders, the problems I saw DIDN'T occur in
professionally built engines. Hmmmm....) Small block Fords and Chevies
can take a LOT of hotrodding before they start tearing themselves up, IF
they're done right. Blowing a dipstick out sounds like an extreme
case--blowby from improperly installed rings, clogged oil return
galleries, something like that was creating an incredible amount of
excess AND unrelieved crankcase pressure. Simple pumping pressures from
the pistons are pretty unlikely to build the kind of pressure you've
described if all the venting systems are operational (remember that as
one piston comes down, adding pressure, another is going up, relieving
it, so it's not quite as straightforward a system as a compressor
dumping all its output to a holding tank.) I've seen such engines
pulling close to 400 hp on a dyno when I used to hang with the racing
crowd, which is close to double factory numbers (and they're capable of
even more), and they didn't blow seals--everything else would break
quickly, but that's from overstressing parts, not crankcase pressure.

And, as you said, your engines were far from stock, so I'm still open to
seeing a current engine in good shape develop the kind of crankcase
pressures required to blow seals without GROSSLY overfilling with oil.
As another poster put it, the fact I haven't seen it doesn't mean it
doesn't occur, but I've seen and been in too many discussions with
engineering/builder types and busted enough knuckles getting up close
and personal with engines to believe it's the problem people think it
is.

Rick

 

[Carl 1 Lucky Texan]

Speaking from experience with '78 Honda Civic, working on a car with
valve covers and oil pans off, over several weekends, possibly even
outdoors, can cause a lot of 'gummy residue' to develop. In my case it
cause the oil pressure releif valve to not do it's very descriptive
title. It blew the through the oil filter gasket.

Again, given what we were told - which of course is all we have here on
a usenet group, I feel (and Rick's opinion is probably worth at least
100 times mine) you're OK.

As for CAN bad things happen given COMPLETELY different circumstances?
well - H3LL YEAH!!!

Carl

 

[thestick]

thanks
Since the overfill is in ounces and not more, I'm just gonna leave it as
is.

g


Carl 1 Lucky Texan wrote: