What weight oil are you running

I ran ROYAL PURPLE 10-40 synthetic on my 340 for 7 years and 20,000 miles when i removed it everything looked new inside . i used zinc additive for the first few oil changes after that I'd add a little zinc every 2 or 3 oil changes . on my stroked 360 a musing valvoline vr1 10-30 synthetic for now . as long as you use a good oil and change it often enough you should be good , and i have never used a quart between oil changes every 5000 miles