Re: Overfilling motor oil

["Daniel Chenault" <danielc@xxxxxxxxxxxxxxxxx>]

Only thing you need to worry about with overfilling is frothing. If the oil
level is too high, the crankshaft will dive into it every revolution. This
frothes up the oil and, depending on the depth of the oil pump pickup, could
result in the pump trying to suck up froth instead of liquid (i.e.
starvation). As well as froth being thrown on moving surfaces (which could
displace the liquid, again resulting in starvation). I believe most, if not
all, BMW's have windage trays which are designed to prevent this (a plate
immediately under the crankshaft).

It's easy to check; run the engine till it's good and hot, then check the
oil. The dipstick should not show any froth at the top of the level.

- ----- Original Message -----
From: "Mike Wilkens" <wilkens@domain.elided>
To: <bmw-digest@domain.elided>
Sent: Saturday, September 30, 2000 1:32 PM
Subject: Re: Overfilling motor oil


> Alan, thanks for responding.  I am not stressing over a dealer overfilling
by
> 1/2 liter, but I am curious.  Regarding the apparently common practice of
overfilling
> M3s, I do not race, so I don't need to worry about oil starvation.  Nor
does my
> car have noisy lifters.
>
> The service manager volunteered that they use two oil spigots, one for
Porsches and
> one for BMWs.  I think you're right that they squirt some chosen amount of
oil in
> and don't bother to check the level.
>
>
> Mike wrote:
> >> My dealer has apparently overfilled the motor oil twice.  (98
3-series.)
> >> In both cases I had
> >> checked the oil the morning after, and the level was above the dot,
which is
> >> above the upper
> >> notch.  The first time, I drove back, they said they redid the oil
change,
> >> and when I checked,
> >> the level was right at the upper notch--right where it should be (I
think...).
> >>
> >> Now they overfilled again: it's above the dot, which is at least 1/4
liter above the upper notch.
>
> Alan wrote:
> >Are you actually stressing over this?  1/4 litre is nothing.  Most people
> >who autox or track E36 325/328/M3 overfill it by a quart on purpose to
help
> >ensure that the oil pickup doesn't suck air on hard cornering.
>
>
> >>The upper notch is the fill-to point, right?  Why would a dealer
> consistently make this mistake?
>
> It probably actually takes a fraction less than a specified number of
> quarts, so they dump them all in and not worry about it.
>
>
>
> --
> Mike Wilkens
> Manager, Platform Development
> Inxight Software, Inc.
> Tel (408) 969-7455
> --
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