, in the 7 or 8 of them I've owned, I've had great luck and had none of these problems. .
I've have owned many over the years, probably well over 30.
I have not had a single major failure except one. That in the 87 Suburban. The former and original owner had it "condemned"by the local Chevy dealer at 200K. It had a bad engine knock, and none of the heating-cooling controls in the dash worked. Dealer said the engine was blown, dash controls all bad, etc. So, I bought it for $500.
Put new injector nozzles into it, along with a water pump and a vacuum pump pod -and it ran like new. This was J-code, 3/4 ton 4WD. TH400 trans and 3.73 axles. So, going down the highway, it was screaming at 75 MPH.
I maintained it well over the years and just about every moving part on that truck wore out at least once. Even the spilnes on the rear axles. But that engine ran like a clock.
One day, when it had just turned 520K miles - going down the highway - it seized with no warning whatsoever. Wasn't hot, wasn't working hard, had great oil pressue, ran smooth, etc. No warnming signs at all. Just instant siezure at 75 MPH. I was 120 miles from home.
When I finaly got it home on a flatbad, and got it torn apart - I found the crankshaft in three pieces and two main bearing webs completely pulled out of the block. I assume the block main-webs had been cracked for years - and finally let go. When they did, and the crank lots support, it snapped into pieces. That's my guess, I'll never know for sure.
So, yeah, 520,000 miles sounds fantastic, but I'm still ticked off over it. Engines should die slow deaths when not abused. Not go like this. I'd be happier if it only got 200K and starting eating oil, knocking a little, starting hard, etc. That way I'd be forewarned.
So, now all the 6.2s make me nervous. Any that I plan to use for any serious miles get the pans pulled and checked for cracks. If no cracks, I assume I'm goot for at least another 100K.
I just pulled my 86 K5 turbo-6.2 mini-motorhome apart today. 140K . I've got the trans and front axle out for some changes anyway. To my pleasant surprise, no cracks. Also reached up and checked the timing chain and it's got 9/16" side-slop which is within factory tolerances. But, I found 1/2 the rear-main seal missing and I'm having a miserable time finding a way to fish it out- so I can fix it. It's the old rope seal.
Last summer we were on a trip, and all of a sudden this Blazer started pouring engine oil on the road. A huge leak. Almost a quart per mile. Ends up, the oil filler cap had fallen off, and stopped the CDR valve from working. I got a ride to a NAPA, got a new cap - along with new Rotella T oil - and it didn't leak a drop after that. But, seems it somehow blew out half the seal.
So, now I'm ticked off at GM again - which is silly. Many older engines had rope-seals. I don't recall ever having to change one before though, with the crankshaft in place.