mixing oil
 

bought a few cases of valvoline racing oil(v-1)with the good supply of zinc in it. i got 20-50 and i will use it in my drag car as is, but i have a 408 SBC with about 525 hp , built for the street with all the good stuff. the engine builder says 20-50 is overkill (too heavy) and i should use a 10-30 weight. what do you guys think, and if it is too heavy, can i mux a lighter weight valvoline race oil(same stuff) to thin it down a bit. any ideas what weight to use and what will be the end weight of the oil if i mix it up thanks chevy art

I think it depends on the bearing clearance, i personally run .002/.003 clearance on the rods and mains, so 20/50 fits my aplications, i run HX bearings in everything i build with a std. crank. If you have less than .002 clearance, then 20/50 is too heavy.

JMO

Zip.

much agreed here.ive heard you shouldnt mix weights of oil but i have on my everyday cars,the twenty plus years of driving and changing oils on a regular 3000 mile interval,ive had virtually no engine wear issues!

currently i change oil for mother in law car and my 7 vehicles, so many times i use what i have.but for the chevelle i have it gets nothin less than brad penn 20-50.great for staying slippery seeing as i put nitrous in 'er :D

oil weight
 

think i willstick with all you guys and use the 20-50 just as it is. thanks for your inputs chevy art