Engine is a 2.0l zetec when i start it it goes to about 30-60 psi but the hotter it get and longer running after 5 mins the pressure goes to 0, the dash light dosnt illuminate thought.
Have had new filter and oil any ideas.

If the oil pressure goes to 0 then I would be inclined to check the oil pressure gauge/sender. I assume the oil light is on before you start the car, and goes off when running 9obvious, but they go faulty too)
0 oil pressure should cause some odd noises PDQ....but a fair chance the worry gauge is playing up.

I had a lot of oil pressure problems with my vauxhall redtop - showing pressure when cold, then dropping to near enough zero when warmed up. Turned out to be firstly the oil pressure relief valve (in the pump body) first, (which meant the oil was not being pumped around the engine!!) then when I fixed that, I ended up replacing the oil pump completely. Now its fine.

Don't automatically think its the pressure gauge - especially as it registers a pressure when cold - oil is thicker then, and can't be bled out of tiny clearances / wear until it warms up.

The standard low pressure light comes on at about 5psi. When over 100deg my oil pressure is around 10psi at tick over. Thats a rebuilt engine with new beaqrings ect.
This looks to be inline with what most others are getting on a zetec. The oil is thinner than lots of other stuff @ 5w/30.
As long as your getting good pressure above tick over I wouldnt worry. As for your gauge, it could just be wrong.

"As long as you get good pressure at tickover I would not worry"

I bloody would, you need 8 psi per 1000 rpm.
We run our engines hard and at high revs, oil pressure is all.
Check sump pickup for crap, just stripped an engine and found sump gasket sealant all over it, cleaned it out, pressures now good, 4 to 4.5 bar stinking hot and pressure rises as expected with revs from idle
I get goof base pressure from idle which is constant till the oil gets hot then I get a slight drop which is recovered with revs

The hotter it gets the worst the pressure.
When i rev it the oil pressure goes down the more revs and hotter it slowly reaches 0.
Took for a test drive down the lane couple hundred yards started to overheat temperature over 100 water not circulating properly, and oil pressure dropped, but dash warning light didn't come on, but did make a very strange noise from somewhere in the engine bay twice like a screech when you try to turn over the starter when the engine is running

A change in Oil pressure is an engine health symptom.
High oil pressure is not an end in itself.

Actually an engine doesn't need oil pressure at all what is needed is copious oil flow into the bearing

It is a common misconception among non-engineers that the pressure from the oil pump keeps the bearing surfaces apart, metal to metal rubbing within the bearing is prevented by the bearings internal oil pressure which is generated by by hydro-dynamic lubrication. This internal oil pressure is many times higher than anything the oil pump can generate.
http://www.marinediesels.info/2_stroke_engine_parts/Other_info/hydrodynamic_lubrication.htm

Now given all that an indicated 0 psi when hot this is a symptom that should be looked at, most of the possible causes have already been mentioned.

(1) Stuck relief valve
(2) Worn oil pump.
(3) Normal wear on the bearings.
(4) Oil temp v viscosity

I suspect it is just down to normal wear on the bearings and oil pump, I suspect dropping the sump fitting a new set of big end bearings, clean the relief valve and oil pump suction filter and change the oil pump will bring a big increase.

However before doing that if the engine is running on 5w/30 try 5w/40 or even 5w/50 and measure the oil temperature if the oil temp is high consider fitting a cooler and thermostat.

But don't be tempted to put a very high viscosity oil or add an oil thickening additive into the sump.



[Edited on 12/5/12 by britishtrident]