Below image analysis on my rebuilt 94. I rebuilt as a 355 in 2023 after spinning a rod bearing. In 2024, it munched a rod bearing up a bit (didn’t spin) but the crank survived. The bypass in the oil filter adapter was deleted, so I felt fairly confident cleaning the pan, installing a new oil pump and rolled a new set of bearings in with the engine still in the car and drove on. Drove hard too but did lower the fuel cut rev limit in the pcm of 5500 (previously was spinning 6400), leaves some power on the table but feels safer. The engine did have 2 quick succession oil changes after the repair and then this oil from the analysis was used from May-Dec 2024. Engine ran and sounded great during that time.

The copper level looks a bit high which has me worried about bearings, but the commentary in the report is more reassuring. The pan is coming off this motor soon to be replaced (currently an F body pan and getting a proper corvette pan). As much as I don’t want to disturb it, debating pulling rod caps for a look. Thoughts on the below?

 

I remember your thread from last year and the pics of the crankshaft, and that you replaced bearings and left the crank as-is.

Lead and Copper and Tin are all bearing material. While there may be some residual lead and copper from the original failure, this is the third oil change since the bearing change. My interpretation is that the lead and copper are from the new bearings, not residual. I was skeptical that the repair would last and this analysis suggests that it didn't. When the pan comes off again, I would definitely look at the journals where there was crank damage last time.

"Silicone" can be from gasket makers and sealants. It is also an indication of Induction air filtration efficiency. Its probably gasket goop. "Air filtration" issues (usually a K&N) usually show indications in the teens. Not 80-something.

You redacted the header information that contains the oil viscosity and miles in service. The SUS Viscosity "Should Be" values are based on the oil's viscosity rating. It looks like it may be 5W-30? 56.4 with a minimum of 55 suggests the oil has thinned. Along with the low flashpoint, I'd take a look at your fueling. Could it be a tad rich-ish causing oil dilution? The .8 for "Fuel dilution" is a little higher than I see on reports of gassers.

Here's a Blackstone for my LT5. I had run the oil 5,050 miles and was curious as to what the wear metals were. I probably shouldn't have sold this car, this engine was hardly wearing at all.
Cheers


1990 ZR-1 Oil Report. Castrol GTX 10W-30, 5,050 change interval. Compare the values to the Universal Averages which are for a 2,400 average interval.

 

It is 5w30 M1. The first two oil changes (I think I did two but honestly can’t recall - it was definitely at least 1) was a run up to temp and dump it out. I hadn’t recorded the miles at the time the analysis fill went in and I guessed 1500. Per the datalogs and wideband info the only time it’s rich is when it’s cold. Probably too rich, but I’m no good at tuning without o2 info, it was guesswork until the motor felt like it ran right - that meant adding a considerable amount of fuel. I didn’t think too much of it since it’s in open loop only a few minutes. It was #7 that had the issue, I’ll pull 7 and 8 caps for sure, I’ll probably ending looking at them all.

 

I would cut the filter open... You'll know without even pulling a cap if you have a problem.

Those numbers aren't absurdly high... but also not great. I like oil analysis reports but they're also just a tool. I've had engines that just threw a lot of metals and lasted forever... some are like that. Other parameters help build a bigger picture.

That being said, sounding good isn't an indication of no issues. Had an engine spin a bearing years ago. Drove fine, sounded fine had fine oil pressure until it didn't. Started it one morning and it knocked. Shut down and restarted heard it again. The crank was so chewed up it couldn't be turned down any further and I needed a new one. That didn't just happen on those 2 ten second starts but it made not a noise until the very end... just food for thought.

heck a used engine I bought for my boat had a cam and bores that looked like the surface of the moon and that made not a sound either. The lifters were so cooked once it got warm they stuck in the bore. My machinist (didn't have the time) called me after he pulled it apart and asked how it ran. He was shocked as I was when he showed me everything. Took a .060 over on a standard bore to clean up. Thing purred. But that's what I get for trusting the "fresh rebuild" from a mechanic.

 

I bought a dedicated filter cutting tool a few weeks ago and did cut it open. Purolator Boss line of filters - built like a tank. No glitter found in the filter media. No metal visible to naked eye.

 

I would move toward inspection then personally.

 

I completed the inspection of the rotating assembly. The rod bearing all looked fine with none in a condition that I wouldn’t re-use - that said, I didn’t reuse. I had a new set of King bi-metal aluminum bearings in hand and those went in. Everything plastigauged at 2thou. I inspected the mains this time and found that the thrust bearing had some wear on the flywheel facing side and the likely culprit behind the elevated copper levels in my oil sample. This was the only bearing where some of the copper layer was visible. Thrust bearing was replaced with a bi-metal aluminum variant and I had 2 thou clearance on the plastigauge there. I did go back to a sharktooth pump and hi pressure spring. It was about 80psi cold start and I have not run it long enough to get it warm (ran into an electrical gremlin with a bad KS). That said, bottom end sounds just fine. I do remember the machine shop checking my crank end play but don’t recall the spec. So I’m a little worried about that thrust bearing. I know the ZFs clutch loads up the thrust bearing (I’m not one to sit at a red light in gear) so I’m not sure what normal would look like but I wouldn’t imagine seeing any copper on that bearing with so few miles to be quite normal.