Thought I would run an oil analysis on my US early '86 automatic 5L 32V. Have close to 169,000mi on the clock. Anything I should be checking?

She runs fine as in. Leaks oil from the oil pan, need to replace gasket among other things when I hopefully pull the engine this winter.

 

Two things: Copper is a concern of course, which points to bearings (mains and rods). And the two most likely candidates would be the crankshaft thrust-bearing and the rod bearings. So top of my list would be a check of the flex-plate clamp and a careful check of the crankshaft end-play for thrust-bearing wear.

The other thing I see is viscosity (cST @ 100C of 13.95) which seems low. I am used to numbers in the 16-18 range for a 20w-50 oil.

What oil are you running? How many miles on the oil when it was changed?

 

That Copper number is pretty high. Usually that's wear on main bearings. Copper can also show up from any bronze fittings you may have installed in the motor that aren't OEM - higher Copper ppm shows up in UOA from marine engines for that reason.

For comparison, here's a series of UOA reports on my old 79 4.5L motor up to when I blew the head gasket. Don't know why the fuel dilution in this sample was higher, but doesn't matter as this engine is not in the car anymore. I'll be running the sample that is in the car pretty soon and will see what it shows. If the same, probably need to rebuild the fuel distributor.

The below makes a pretty good case for why Shell Rotella Dino oil may not be the best choice for these motors, though info use their T6 full synthetic in some of my non-Porsche other cars (BMW, Infiniti, GMC pickup).

 

No new bronze fittings that I have installed as far as I recall.

I'm using Mobil1 15-50, probably had about 4,000-5,000mi on it. Last time I checked end play and relieved tension on the flexplate was probably about 5ys ago when I did the TB/WP. I was within spec then. I'll go underneath and relieve and measure this weekend.

 

please post results here for us. Good luck and thanks.