I just replaced a 2005 4.3 at 176,000 miles. I am the second owner and I knew the meticulous first owner. He had lost an oil pump and a timing chain during his tenure. For a good while it had a broken or weak valve spring that would dramatically limit the performance at 94 mph. Various other operating issues, low -ish compression all around and finally #6 showed 10-12 psi compression. I pulled the plug at that point and replaced the original engine with a $500. used engine from a yard I trust.
So apparently there is at least one which refused to run forever.
The rest of the truck is nice but the original 4.3 engine wasn't quite up to par somehow.
Originally Posted by 901Memphis
I think the 4.3 is the exception, it runs forever on anything, any flavor. I don't think i have seen one of these engines that didn't outlast the rest of the truck.
I think recommending any API SN 5w30 is appropriate.