Says who? Show me where a factory Chrysler service manual says to run 20/50 in an engine. Never have and never will. Oil viscosity has little effect on oil pressure.
A good example would be some of these newer engines where manufacturers recommend 0w20. The reason for this is to get oil to the engine QUICK on startup. Once the oil reaches operating temperature, it changes to 20 weight viscosity. They bury the oil pressure gauge cold when the oil is 0 weight.
When you spout off an opinion, make sure you let everyone know that, because to my knowledge, Chrysler never recommended 20/50 for any of these older cars. Mostly straight 30 weight and 10w30 as multi viscosity oils came into vogue. I've rarely even seen straight 40 or 10w40 recommended.
You've been watching too many Castrol commercials.
And engines don't last long anymore? Puhhleeze. What planet are you living on? Pluto?
Newer engines are lasting longer than older ones ever did and it's due in part to newer oil technology. Fuel injection also plays a role. I have seen more newer engines than I ever did old ones with 200K plus miles on them.
You are just dead wrong.