Just a little info to add to this thread. I just have a 30k service completed on my 92 500E and had the shop do a compression test as well. Here are the results;

1 - 190
2 - 180
3 - 190
4 - 185
5 - 180
6 - 180
7 - 180
8 - 185

So, if I take the guages accuracy as gospel, my cylinder average is 183.75 psi and the 10% rule would let 18 psi swing up or down.

What do you Technicians think, does this sound accurate? What do you think Guido? Not sure if this was don Hot or Cold, whats the difference?


BTW, engine has 173600 miles on the Odo and has had dino oil all it life until 5k ago.