Oil Presure. What is "normal" - PeachParts Mercedes-Benz Forum

#1 10-16-2003, 06:33 PM

Hey everyone, well yesterday I decided to change the oil in the merc. Before I was using Penright 20W60 oil, and whever I drove the car the oil presure guage would be showing 45 all the time.
This oil change I purchased some 10W50 oil on special, So I put that in.

I have noticed that when i'm idle at a set of red lights, that the oil presure guage is showing inbetween 30 and 45. I'm probably worrying about nothing, but, is this normal?

sixto · #2 10-16-2003, 07:45 PM

The key is that it pegs when the engine is above idle such as when you're moving. If it goes below 15psi at idle, check back with the forum.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD

MikeTangas · #3 10-17-2003, 01:31 AM

Your pressure is perfectly normal for your vintage of Benz. My 4.5 shows almost exact numbers running 30W dino, ~25 at idle and pegged underway.

dougp · #4 10-17-2003, 01:34 AM

thanks Mike and sixto - you answered my question in another thread. Guess I should read more and post less

haasman · #5 10-17-2003, 02:14 AM

It is interesting to note that domestic cars loose their idle oil pressure rather quickly as they age. I remember this from years ago.

I had a discussion the other day with a friend who couldn't believe the oil pressure on one of our 10+ year old cars. He insisted that I didn't know that the engine was rebuilt, but in reality Benzes just seem to keep a strong oil pressure through the life of the engines.