Oil Pressure


My engine was rebuilt 4 years ago, due to one reason or another it wasn’t finished until the end of last year, it’s only covered 30 miles since then because of clutch issues.

My oil pressure seemed a bit low, so seeing that the oil was 4 years old etc I changed it for Millers 10w 40 running in oil (filter changed too).
On start up the oil pressure rised to 6 bar, after 5minutes of idling it dropped to 2.5 bar, 10minutes it settled at 2 bar. The pressure rises fine when I rev the engine/under load, but as the revs drop the oil pressure touches as low as 1 bar for a split second (warning light/buzzer sounds) before settling back at 2 bar.

Does that seem normal?!

I’ve got a Defi BF gauges/senders, so can’t see them being at fault, checked the sump pan for dents, which is fine. Could it be that the oil is too thin?
The oil pump was checked when the engine was rebuilt and was in excellent condition, is the oil pressure relief valve another possible cause?
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New Member
was the crank crided if so graded bearings are needed they might of put strd back on ,when i rebuilt engine some years ago had the crank reground then polished put strd bearing back on they were the wrong ones put graded once in oil pressure was spot on then

Fast Guy

Staff member
Is all the above at idle?

Warning light/buzzer is that on the defi gauges and is it set by you?

Oil pressure at idle should be at least 0.98bar so I don't realy see much of a problem.

It's supposed to be something like 3.4-4.4bar above3500rpm I think. Do a search I've put it on here loads, but not very recently.

Also don't let your car just sit there idling for ages, it's doing the engine no good, get in it and drive it.


Cheers for the feedback, just had a read through old threads.

Yeah the above was at idle, car isn’t legal yet, getting an MOT next month, so not really able to drive it, although I did take it for a quick spin on a ‘private road’ earlier, oil pressure seems fine under revs whilst driving.

I was just a bit concerned the way it dropped to 1bar for a split second before settling at 2bar, but from reading through the old threads it seems my oil pressure is fine other than that. Like you say the Defi BF warning light/buzzer is adjustable so I’ll set it at 0.98bar.

red reading

Active Member
leaving the car on idle means that the oil pressure is very low,the water pump is not circulating very well ,which means that heat is being trapped in the engine= not good best thing to do with a car is get in and drive it ,let it warm up before you thrash it and let it cool before you stop it