Oil pressure light in instrument on dashboard

[betjent]

Hi There

Yesterday I discovered that my oil pressure light in the speedometer comes slightly on at slowrunning. Only with the engine hot. (the oil pressure is lower at hot engine) When I accelerate the light switches off.
Now - the car has been standing for a while ( 14 days or so) without driving. Has anyone experinced anything like this .
The engine is in good condition. Oil new. And there is enough oil on.
The oil pressure switch is 2 years old.
Anyone knows what the trouble is ? Is it electrical or mecanical ?
Dont say its the oil pump !!!

Please help - im desperate

cheers
Carsten

[Willie]

If your engine is in good condition then usually this is a faulty oil pressure
sender switch( to the rear of the dizzy). If a new one does not cure it then you really need an oil pressure check with a gauge. This will show if the pressure is too low on tickover and if it gets up to the correct 60 psi when
running.

[bmcecosse]

It's quite normal with an older and therefore worn engine. You could use 20w50 oil - which is a bit more viscous. The real solution is a crankshaft regrind and a new oil pump - but your engine will run as it is for many years to come.

[rayofleamington]

The engine is in good condition. Oil new

What oil did you use? I've had this on a worn engine with cheap 20/50 oil. I changed back immediately to Castrol GTX and that cured it.

[bmcecosse]

Well - there's not much cheaper than Asda 20W50 - at £ 2.74 for 4.5 litres - and it gives me no trouble at all, and 70 psi oil pressure even when scorching hot! You could check the oil pressure relief valve - just to be sure it's not stuck part way open. You say the engine is in good condition - how do you know that ? You could fit an oil pressure gauge - it's the only extra gauge worth fitting - but it may just give you sleepless nights. Ideally you should have 10 psi pressure for every 10 mph in top gear - up to 60 or 70 psi depending if you have boosted the relief valve spring, or not!