...

Danny...anywhere from 60K -100K is the normal failure area for the manifold. I've seen one come off a 2000 at 110K with no signs or issues. It's a big questions as to when or who.

GMC.. Prestone Long Life is a good one, as is the green stuff.

great, hopefully i'm safe then.

for the record, i'm going to have a coolant flush done tomorrow. it doesn't look like the dealer did it (probably not, since GM doesn't recommend it). My mechanic uses the green stuff. just short of 40,000 miles, will this potentially help me avoid the UIM/LIM failures or is it still just a matter of time in most cases?

That's a tough one. Many believe Dexcool is the cause of the deformed gaskets etc. However... more thinking on it..showed me that the gaskets fall apart in areas where there is no coolant. And GM has begun producing a different gasket ... not a different coolant. While Dexcool is obviously not the answer to the worlds problems as they hoped..I'm not 100% that it's the cause of deformed gaskets.

As well...I changed gaskets recently.. no dexcool at all in the system and they were deforming a little after 1.5 years.

so i've read different things here..

i have an 04 with the L36... does this mean I have an aluminum LIM already or not? If so, does this mean I just need to have the UIM work done (pre-emptively of course)?

i want to get it done before anything happens.

I too have an 04 with L36, and no it does not have aluminum framed LIM gaskets. They have the same junk plastic that causes problems. I changed mine as to avoid future issues.

I wish I knew what my car had for gaskets. I know I got the newer stock upper intake when mine went. And I'm 99% sure they put in the new LIM gaskets with that repair.

But then the engine blew up, probably due to coolant in the oil, so I have no idea what's in the new engine....

I am not aware that any L36 or L67s came from the factory with the aluminum-framed LIM gaskets. To our best collective knowledge these didn't appear on the scene at all until mid 2005.

IMO, always assume that you DON'T have them unless you put them in yourself or specifically had them put in.