UOA-08 Gen4 5.3 LY5 LS

[donjetman]

1951 Chevy 5 window Resto mod pickup:
I recently decided to do a used oil analysis (UOA). Results were not what I expected high copper & lead (bearing material). At 11,000 miles maybe the engine is still making brake-in metals? The oil was Mobil 1 0w-40 Euro, 11 mths old w/400 miles. Oil filter was Purolator Boss PBL22500 w/400 miles. I cut open the oil filter, and it was clean.

I decided to pull the oil pan to take a peek at things. There was NOT any varnish as would be expected in a low mileage engine. But there was some mud like sludge in the bottom. I pulled a main & rod cap they looked okay. There are small scratches but nothing I could catch a finger nail on. Clearance on each was .0015" which is okay. I talked with a machinist and engine builder friend of mine and he said the copper and lead must have come from the cam bearings. LS engines are famous for cam bearing wear. The sludge/mud in the bottom of the pan is a mystery?

We purchased it in 2013 mostly finished with 170 miles on the odometer. The seller/builder purchased the engine from a scrap yard that said it had 8,000 miles. The 2008 Gen4 iron block LY5 5.3 comes from the factory w/AFM but no VVT, The builder/seller of the truck had the AFM tuned out before we got it. It runs great, no ticks, knocks, etc, and gets 18+ mpg on ethanol free 90 octane unleaded. I believe this engine has 11,000 miles since GM factory NEW. We bought w/170 miles. We have put only 3,000 miles on it since we bought it in 2013. It has had 3 (or more) oil/filter changes that I know of.

I cleaned the pan out and put it back together.

 

[donjetman]

Here's the Blackstone lab report and more pics:

The original o-ring was in good codition, but I replaced it anyway and added the 2nd bolt bridge.

 

[donjetman]

#3 Main journal & cap, .0015" w/plastigauge.

 

[donjetman]

a rod cap & bearing, again clearance of .0015"

 

[rdezs]

I would dump the oil and switch to a 5W30.... I don't think I'd ever run a zero weight on LS cam bearings, unless I lived in Prudhoe Bay Alaska.

How is your hot idle oil pressure? That would likely be the first place you'd see evidence of camshaft bearing wear. You don't by chance have the trunnion bearing kit with the solid bearings? Those are known to shed material. If not, I'd go with a 10w30 and check it again at the same mileage with an oil sample.

 

[rdezs]

Do keep in mind that GM line bores the camshaft bearings after installation, which might suggest that the bore cast in the block is not in perfect alignment. (As noted by some of the blocks clearly having copper exposed after being line bored.) The end result with a camshaft bearing change, is that you can't match the factory lineup perfectly. You may in fact have some extra wear on a couple bearings due to this. Cam bearing failures after replacement unfortunately seem to pop up on LS engines more frequent than other engines.... I always figured it was because of this. There's no machine shops in my area that are set up to line bore the cam bearings after installation. I just wonder how much it would drive up the cost of a rebuild. (At that point, it probably becomes advantageous to buy a new iron block from GM)

 

[donjetman]

Engine is bone stock other than exhaust and air filter. It is never driven hard and weighs only 3500 Lbs, so its light & nimble and never see's much load. Mustang II rack & pinion, RideTech 4 corner air ride, C4 Corvette IRS, 4 wheel disc brakes.

 

[j91z28d1]

looks like a fun driver.

that gunk in the pan is weird. seems like to much to be bearings to me. especially with nothing in the filter.


I got nothing. way worse than my 170k pan I just had off yesterday. it only had build up on that little troth that runs to the drain plug. everything else was just varnash.


some crazy amount of assembly lube?