1990 GMC 350 TBI, Pennz Plat 5w30, 5200miles

[Santo Fontana]

This was done right before I snapped a thermostat bolt and ended up having to remove the intake mani. This led to a series of small performance upgrades like an edelbrock intake, msd coil, tbi porting, open element air filter, catless exhaust, etc. It will be interesting to compare this to the next UOA.
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[tig1]

Even though your engine shows some metals in the UOA I wouldn't be too concerned as often GM engine show high metals, but are capable of very high miles. Metals in a UOA often do not translate to engine wear. PP is a great oil so don't blame the oil.

 

[addyguy]

That's NOT PP.

PP doesn't use magnesium as a detergent, and it isn't that thick. I'd check that they gave you the right report!

What was your top-off oil?

 

[Santo Fontana]

hmmmm there could have been some rotella 5w40 mixed in. i think thats what i ended up using as top off. I also I also mixed the very last drops of an old bottle of sx-up in there.

 

[webfors]

Originally Posted By: Santo Fontana
hmmmm there could have been some rotella 5w40 mixed in. i think thats what i ended up using as top off. I also I also mixed the very last drops of an old bottle of sx-up in there.


that explains it! The truck is already 20 years old. Any miles you get out of her now is what I call 'bonus miles'

 

[Santo Fontana]

yup. but its got some sentimental value since my grandfather gave it to me to I am keeping it as long as possible.

 

[addyguy]

I remember when you posted that first UOA with Syntec blend, it looked pretty bad.

I've always wondered if you kept the truck going.....good show keeping it on the road!

 

[ARCOgraphite]

Bet the report would be MUCH better without mixing brands on topoff. On a GF4 oil It ABSOLUTELY breaks the add pack balance.

 

[ZZman]

Maybe this goes to show how much better engines are being built now.

Any idea if many of these older engines showed this type of wear?

 

[cchase]

Originally Posted By: ZZman
Maybe this goes to show how much better engines are being built now.


Not if you see the wear metals a lot of the LS-based (truck LQ engines included) spit out these days.

For reference though, my long stroke 305 TBI engine had 8.3 ppm iron per 1000 miles.

 

[ARCOgraphite]

Are they still "net building" engines with a wide tolerance stack? Goes to show you can make a piston too short and light - I guess they found the limit. Maybe they only match piston-bore on the Z series vettes?

 

[ProStreetCamaro]

Originally Posted By: ARCOgraphite
Are they still "net building" engines with a wide tolerance stack? Goes to show you can make a piston too short and light - I guess they found the limit. Maybe they only match piston-bore on the Z series vettes?



They went back to matching pistons. our 07 2500HD and the 07 yukon I just bought are both quiet as a mouse. My 99 SS I just sold had some minor piston slap during warm up. I think I read around 06 or 07 they went back to hand selecting pistons to fit the bores correctly.

I dont think short and light has anything to do with it. You should see how short and light the pistons are in my long rod (6") 383 stroker. We under boared the block then honed each cylinder out to acheive the perfect clearance for each individual piston then file fit the rings. That engine has no piston slap.

This is my piston here

 

[Santo Fontana]

when I go to get parts for the truck I regularly see trucks with 300k mi +. Saw one with 430,00. last time I was there.

I know this truck was a little neglected by my grandfather. He let me do one oil change a year and wouldn't let me touch anything else. He never had a problem with it so he was right in a way. But now I am breaking every bolt I touch...It still runs very smooth and quiet.

I drive it 100miles a day and the new intake mani and other mods raised my mpg from 11 to 14. I still need to get it tuned though. I datalogged the other day and it is showing more knock counts than I would like to see.

Oh, and my next oil fill is kind of weird too. Its half spertech 5w30 and the other half is a mix of all the synths I had left, M1, PP, Castrol Syntec Edge. Ill try it with one oil next time