High Oil Pressure Reading?

[T-RONE]

Having recently changed my oil in my 87 carrera, I switched from Mobil 15w50 synthetic to 5w50 synthetic. The reason for doing this was at the recomendation of my mechanic due to a variety of temperature ranges. Now while driving I get a higher than normal pressure reading then before. ie(3500+rpm = 5bar) Is this due to the lower weight of the oil? I know a high pressure reading is ideal but this doesn't seem right!

T-RONE
__________

87 carrera coupe

[JK-81SC]

My guess is the high oil pressure is due to the lower air temperatures.

Does the higher oil pressure drop after driving for 30 minutes? After the oil warms up it should be the same as before the oil change.

[T-RONE]

No, the oil pressure remains high even after 30 minute drive.

T-RONE

[T-RONE]

BUMP

[ael911]

I am not sure how much psi 5 bar equates to, but my oil pressure is usually double of the rpm. On a normal day at 3500, oil pressure would be around 60-70 psi. If it is a really hot day, I will see about 40-50 psi. Theoretically, pressure should be slightly lower by switching from 15W to 5W. Are your thermostats working correctly? Is oil temp normal as usual?

[Gunter]

T-Rone: Still driving now in Edmonton? Isn't it time for winter storage?
Any way, most people do not use synthetic because they found that the oil/air cooled engines in a 911 leak less with Dino oil.
I go along with that. Use synthetic in water-cooled engines.
For me: 15W40 Dino in the Spring and Fall with good results.
I like 15W40 because it's a Diesel application; high pressure stuff.
In the Summer: 20W50 Dino for me.
As for your higher pressure reading: Thinner oil should get you a slightly lower reading. Unless I am missing something.
What is your pressure at 900 RPM?
It should be about 1 bar, slightly under.

[T-RONE]

Thanks for your input everyone, Dr. Gunter this was just an observation I made before winter storage. I just now found time to post.

As for my pressure reading, it is about one bar @900RPM but anything over 3k it pegs out at 5 bar.

T-RONE

[88-diamondblue]

I did a rebuild last year and my oil pressure at anything over 2700 rpm is pegged at 5 bar. This is the same as before the rebuild. Sound about right IMHO.

[Hugh R]

Are you sure your gauge is actually working. Does it ever go below 5 bar, or is it pegged. If pegged, (i.e, when ignition on but not running), then you'd have an open connection to the sending unit.

[T-RONE]

Hugh, the guage is working properly. Once over 3k it is pegged then it drops when rpms fall. I've read some other threads, maybe I'll try cleaning the faston tab and go from there.

T-RONE

[Mysterytrain]

Are you using the cam line restrictors?