Low oil pressure
Yep, I must be killing my engine... I have a 215k mile 1993 Chebby K2500 that has always used 5w30. I recently switched to 10w30 a few months ago.
But anyways, you were told to start another thread, but you keep scratchin'. Please take the sound advice given and stop hijacking this thread by arguing for the sake of arguing.
*Edit* Forgot my wife's 2007 Ferd Escape with 150k and still running 5w20. Still getting 25-27 mpg on the freeway.
I believe you might have misunderstood my point, I never said all new engines die early, I just said many newer engines dont last. I also didnt discuss causes like lack of maintenance, freeway miles vs short trip miles or good/poor design. I think we can all agree that the GM V8 is a long lasting engine as are many others, there are also lots of very short lived engines out there. I am glad the posters here are doing proper maintenance and it seems to be paying off with what might be considered higher than norm miles.
I will say that with the thinner oils, you have to be more up on timely changes as all oil looses viscosity as it breaks down(another can o worms). In other words, if you dont change your 0w20 or 5w30 on time, its less forgiving than say for example 10w40. This could be a reason for early failures, I am not sure what is causing it but keep doing frequent changes, it seems to be working well for you and it does for me. Also, dont forget, OP has an OLD engine which is somewhat different than newer stuff, although not much in terms of v8 GM.
I really dont want to argue about oil, I was simply OFFERING a way for OP to determine if anything is wrong with his engine for $25 without pulling it from car. Putting 20W50 in an OLD possibly worn or sloppy engine with new filter will eliminate possibility of bad fram and by watching what changes on gauge, get a better idea of bad bearing, oil pump, plugs drilled for racing(it was a "track" engine) or what ever is causing what SOME agree is probably not enough oil pressure for a 340 driven on the street and certainly not enough for hard use(another opinion).
I was trying to help OP not loose his engine due to what I CONSIDER really bad advise and I believe helping the OP is what the real purpose of this thread is.