Engine longevity and ignition/induction types?

[FLJoe]

I think it's what Kennythewelder said, regarding tolerances, plus better materials, plus better engineering and design. The roller cams help a lot. Better seals mean less leaks and less low oil situations. Better oil helps, too. My own truck is a 96 Vortec 5.7 and the engine is all original with over 500,000 miles on it. I've been religious about oil changes since new, don't hammer it like a lead-foot kid (but I don't baby it, either, including a fair bit of towing an 8000 lb boat) and it still runs about 2000 miles before I need to add a quart of oil. Most of that is either leaking, or going though the valve guides, I expect.

I also have a boat with a 96 Vortec 5.7 in it. Marine applications are terrible on an engine. Think of long, hard running at full throttle, pegged at 4500 RPM, with shocking loads on the crankshaft every time the boat hits a wave and digs in the prop. It still runs like new and uses no oil. That one has an old 500 CFM carb on it, which makes me think that fuel injection has less to do with it than the things mentioned above.

I have a 2005 Pontiac GTP with the supercharged 3.8 V6. I had the heads off at 250K and the cylinders looked like they could have been out of a 50,000 mile engine. All the crosshatching was perfect and no scoring at all. I expect that's good materials, good tolerances, and good oil.