[bmw] <E34> 88 535i Oil pressure

[Ole Jørgen Mæland <olejm@xxxxxxxxxxx>]

Lately I have noticed that in the morning when the engine is cold, the 
oil lamp is on for a longer time then it used to be. Actually it is on 
until just after the 'plong' when the check control says "Oil pressure".

This only happens in the morning and in the afternoon when the car has 
standing for several hours and is completely cold. Under any other 
condition, the oil lamp goes off immidiately when starting the engine.

I have changed the oil pressure sensor with no effect, I have changed 
the oil to semisynthetic Castrol GTX 5 (used to have mobil 1), the 
theory was that the oil was to thin to build up the pressure fast enough.

And I have changed the oil filter including the small 'o-ring' on the 
filter house bolt, the theory here was that the oil would drain from the 
filter housing if the little 'o-ring' was old and worn.

But no, nothing of this cured the problem.

This really makes me nervous, and I'm having bad nightmares about having 
to make a complete engine rebuild...  But seriously, what should I look 
for next? Could it be the oil pump, or is it most likely the bearings 
that are worn?

The car has 230k km (~143k miles) on it and it does not consume any oil 
between the oilshifts. It does not smoke any blue smoke either.

--
-OJ
'88 BMW 535i
'86 Kawasaki GPZ1000RX
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