I don't hear any bad sounds, but I do have 100k + miles, and saw some small metal flakes when I was checking my oil a while back. I also want to know if there is any way I can tell if it will perform as good as a low mileage ls1. Any ideas?

 

If you mainitaned your car well over the years I dont see why it should not be healthy. Just so regualr maintance was done on time and oil was changed every 3k or so.

 

If the engine has been kept up w/ regular maintenance then it should be running pretty strong at 100+k.
What kind of oil/filter are you running, and at what intervals are you changing it?

 

I have only had it a few months and have probably put less than 100 miles on it.

 

mine has 145,000 miles on it and it makes horrible sounds.

other people here are running non rebuilt LS1s with 150k+ on them and arent having problems. it will let you know when its about to go..

 

Hopefully the previous owner took decent care of it. I run castrol syntec 0w30 and a K&N gold filter, I get better oil pressure with that setup than I do w/ the standard penzoil and crap filter the oil change places use. As well as oil analysis results from other LS1's suggest that the castrol 0w30 (the kind made in germany) offers the best protection.

I'd also go ahead and change the tranny and rear end fluid too unless you know the exact mileage at which it was changed last.