Compression test results...

[86Five-0]

I did it after comin home from class which was a 25 mile drive so the engine was nice and warm. Just recently did an oil change to 20W-50. Here are the results: (btw I recorded after each crank and did it 5x, averaging out all the #'s)

'86 5.0 with 135,000mi. on it.
Cyl # Comp.
1 145
2 140
3 145
4 135
5 145
6 145
7 135
8 145

These are the averages I took rounded off, I didn't get anything lower than 137 but listed 135. I did 5-7 cranks until the gauge went no further. First crank shot up to around 90 and last went up to about 190 at the 5th crank pretty consistently between cylinders. Let me know what you guys think.

 

[408stroker5.0]

Not to bad, but could be a little better for a 5.0 especially an 86 5.0 which had a bit more compresion than the 87 & up 5.0's. The 87 5.0 I had in my stang before the 408 had 205,000KM on it, and it averaged 158-165 all the way around! I was very impressed. Overall though, I would say what you have isn't to bad... it could be alot worse. I would take that 20W-50 out as well. Your engine DOES NOT need such a thick oil. It does nothing but rob horsepower and gas milage. Throw some 10W-30 or 5W-50 Synthetic in it and you and your motor will be alot more happy. 20W-50 does not lube or increase your engine life any better.

 

[86Five-0]

Yeah, I had just recently changed the oil and put in the 20w-50. You think it's bad on the the engine? I had been runnin' 10w-30 for almost the past 2 years. As for the compression, would worn out valve seals give me lower compression? The car does smoke a little bit and burns some oil but not that bad.

 

[408stroker5.0]

The 20W-50 won't hurt the engine, but like I said there is no sence in having it as it rob's HP and mileage.