Oil pressure at idle, hot??

[bimmer630]

Whats the usual oil pressure on M20's when at idle, hot engine? I have a set of VDO gauges in my car, my pressure drops to like 10psi but if i rev it up it quickly builds pressure, about 30 pounds when driving. My oil warning light comes on sometimes on summer days when coming to a stop, too.. I think this thing has a weak oil pump but ive driven this thing for a while and never had an issue, besides the idiot light flashing in my face.

I actually switched to 10w60 castrol motorsport oil (M-car oil) because I worked at a dealer and would aquire this oil over long periods of time, a quart at a time.. anyway the pressure light didnt come on as much after switching to this thick oil, but every now and again it still does

[reelizmpro]

I have heard of people complaining on low pressure on turbo cars. I see it myself sometimes but the light just flickers and never stays on. It's made worse by thinner oils and I run a 5w-40/15w-50 blend on my M20 turbo. Shouldn't be an issue on a naturally aspirated engine though. Maybe time to replace the oil pump?

[jlevie]

A freshly rebuilt or new engine should run at least 15psi at idle when hot. An engine with 150k would probably run about 10psi, if it has been properly maintained and is filled with 20w50 oil. A 200k mile engine may struggle to keep the light off, meaning that the pressure is about 7-8psi.

Wear in the pump can be a factor, but in most cases it will be wear in the engine that causes low oil pressure.