Best Engine Oil

['68OrangeSunshine]

I use straight 30 weight in my 292. Sometimes I run 20W-50 weight -like in the winter - not that we've seen much of that in Tucson, this year.
In the 350 in my '71 GMC Jimmy, I use Valvoline SynPower 20W-50 year round.
If I have new old style oil, Service SL, I don't use additive, but if I'm using Service SM, I add a 16 Oz bottle of STP for the ZDDP.
If I could afford it I'd use Valvoline Racing 30.