Astra oil pressure lamp

Hi all,

One of my mates has a D 'reg Astra estate 1.6 that has an intermitant oil
pressure lamp.

When driving on normal roads the car behaves nicely, sounds great (for age)
and runs almost like a new car. If he takes it onto the motorway then after
about 20 mins of 70-90mph the oil pressure light will come on, if he drops
to about 60 then it goes back off. If he pulls over then the engine still
sounds nice, no horrible sounds, still revs fine just like normal. When he's
pulled over and the light is on, if he revs the engine, the light goes out
until it idles again.

Any ideas, I'm going to change oil and filter on it at weekend and see if
that makes a difference because the guy he bought it off did it himself and
we doesn't know what was put in it. I can't tell if it's burning oil because
the seller put 10 gallons of "aircraft fuel" into it before handing it over.
This as far as I know is unleaded fuel with oil added so it seems to blow
small clouds every now and then.This fuel issue is making me more than
dubious that oil is correct.


Any ideas? like I say nothing "seems" to be wrong with it, just this lamp.

Tim

 

sounds like the oil pump is worn and is losing oil pressure during idle, or
low engine speeds, increasing engine speed will just turn the pump quicker
and provide just enough pressure to put the light out, oil pump wear was
quite common on high mileage OHC vaxhalls, not a great deal you can do apart
from use a slightly thicker grade oil to help maintain a certain amount of
pressure, or replace the oil pump.
it sounds like the oil pressure switch is working fine if it is just coming
on during idle etc.