20w50 worked fine in a 96 Neon 2.0 DOHC 4 cylinder in Maryland for 20 years and 250,000 miles, still runs like new. I'm sure we are all overthinking this oil thickness thing.
I've seen the forum gurus argue that 20/50 is way too thick for anything.......and yet, I've seen where people have run it exclusively for YEARS and had great service. I've said it before and I'll say it again. I think in the end, as long as the dipstick says "full" the engine is probably a happy camper. lol
