What should the oil pressure be on an S2?

[frontfloater]

Steve Heath's book has a table on page 23, saying that the oil pressure should be "50-70 pounds at about 2500 revs", but no mention of other engine speeds. My gauge has been showing about 48 at those revs or higher while driving, but it drops to 20-25 while idling. Is that normal, or should I be worried? The dipstick shows oil to the upper mark, and at the last service it was filled with 10/40 semi-synthetic.

[phillpot]

Perfect.

[v8s4me]

frontfloater said:

......... oil pressure should be "50-70 pounds at about 2500 revs", but no mention of other engine speeds. My gauge has been showing about 48 at those revs or higher while driving, but it drops to 20-25 while idling. Is that normal, or should I be worried? ...........at the last service it was filled with 10/40 semi-synthetic.

That's probably nothing to worry about. The readings mentioned in the SH book probably refer to a new engine running a heavy multi-grade oil which is what would have been available at the time the engine was in production. There's lot's of info on PH about oil pressure in these engine. Here's one to whet your appetite CLICK. So long as the pressure remains stable then all should be fine.

On the next oil change try Valvoline 20W/50 mineral oil. That's an old school multi-grade made to modern specifications and superior to anything available when the engine was in production. The heavier grade might give a higher reading in a high mileage engine.

Also bear in mind that the oil pressure relief valve is there to stop the system running at too high a pressure.

[frontfloater]

I should probably have also mentioned - full stage 2 engine rebuild at 34000 miles, now just below 50,000. The temp gauge wasn't going above the white line during those periods when the oil pressure seemed low.

[v8s4me]

frontfloater said:

I should probably have also mentioned - full stage 2 engine rebuild at 34000 miles, now just below 50,000. The temp gauge wasn't going above the white line during those periods when the oil pressure seemed low.

If you're still worried why not fit another sender unit and see if that makes a difference. Then try the heavier multi-grade.
Even on a relatively low mileage engine the tolerances in a 30year old cast iron lump will be much greater than on a modern engine. So long as the oil pressure remains steady when the engine is hot and under load and there's no smoke or funny noises then there's noting to worry about.

This was taken on a French autoroute one very hot day. Mile after mile of high speed cruising running Valvoline VR1...



OK so it's a V8 but it's the same vintage and technology as the Cologne V6.