Big Cube LT-5 Engines and oil samples

[emmvette]

I sample oil when changing to keep an eye on things. I have a 402 and have had steady high iron numbers and a steadily increasing potassium for 2.5 years (coolant leak). The engine has been a 402 for 20 years, and has about 24k miles total now.

I'm curious if others with big cube LT5's do sampling and if their results are typically a little higher than 350 ci LT's. Feel free to PM me or other if your not comfortable posting.

I have no outward signs / reasons to be concerned, yes it uses oil, but no more than any other 1990. No "excessive" smoke, Power is very strong as always, and it doesn't make noise other than a great exhaust note.

The engine is a LPE and so should have LA Sleeve iron liners.

[tpepmeie]

at 800 miles I had 24ppm iron. fresh off the engine dyno after break in was 14. That's a 427 with iron liners.

what kind of cams and lifters are in it?

[tpepmeie]

at 800 miles I had 24ppm iron. fresh off the engine dyno after break in was 14. That's a 427 with iron liners.

what kind of cams and lifters are in it?

[emmvette]

I don't have that info - whatever John L decided back in the day.

[grahambehan]

I don't have that info - whatever John L decided back in the day.

If it's the car I think it is, the cams would be LPE's 239 intake with 221 exhausts.

Graham.

[Hib Halverson]

One thing you have to remember about spectrographic oil analysis is that what you see in the results is "cumulative" because the stuff that oil analysis analyzes is too small to get trapped in the filter.

So, if you change the oil every 3000 miles and see 25-ppm iron you're in much worse shape than someone who changes oil every 15,000 miles and sees 25-ppm iron.

When you say your engine doesn't use any more oil that other 90s...are you talking about 90s with or without exhaust valve stem seals?

Lastly, iron can come from more places than just liners.