Slick 60's

My '66 F250 has an I6 300 in it out of a 1986 F250. It has roughly about 87k on it. I've been doing some research on what types of oil to use it. It seems from what I've seen around the interwebs is older engines need the ZDDP and that most people recommend shell rotella diesel oil in their older engines.
I would only be driving my slick in the summer/fall, so the temps would be roughly 30 at the coldest and probably 80's at the most. Mostly just for cruising and some occasional hauling. I was thinking of running the diesel shell rotella 15w40.
Would this oil be a good choice? Is this engine old enough to need the zddp? And what are other people here running in their I6's?

I run 5w40 synthetic in mine. The 15w40 is not a bad choice. You can run that or Delo, whichever one is cheaper at the time. I have a 1980 300-6 in mine, btw.

Dan

Rotella T 15w40 is in all the engines I own. It is for gas OR diesel engines and the only non Cummins oil that meets their warranty specs.
Tom

my take on the zinc stuff is it applies to newly built engines. If I slid a new cam in something then I will worry about zinc and run brad penn oil, zddp addative during break in and zddp paste on the cam lobes during the install.

If I snag something up that has had years of good oil with zinc in it I cart my butt down to walmart, grab some 10-40 or 20-50 super tec and run it. If you are really worried about zinc in oil either buy the Valvoline vr1 racing oil off the self at the parts store, it says not for street use because it has high zinc in it. Or order a case of brad penn off ebay.

All your off the shelf oil has low zinc in it now, diesel oil, car oil, high mileage what ever because of the EPA. You can spend hours reading stuff on Bob is the oil guy and see what people have had numbers wise for zinc RECENTLY. Not back in 05 when I ran rotella for zinc, all your diesel oil has been re formulated due to ultra low sulfer, DPFs and all that emission jazz.

My opinion, read up were people have sent oil out to get tested. That's the black and white info. I'm sorry I cant provide it but I don't send my oil out. I know that I use brad penn in my new builds and wally world on sale whatever in all my other stuff except my Cummins. Ive been reading about zinc since I bought a Buick Grand National a few years ago and when ever ive swapped a cam on an engine or rebuilt and engine. This guy has never been able to afford a Hyd roller cam that wouldn't be effected by it.

I run pennzoil 10w40 in my 65 with a 240 six with no problems I also ran it in a 86 bronco for well over 200 thousand miles and was running great when i traded it off.

Thanks everyone. I'll be sure to read through bob is the oil guy, thanks for the tip.

I run the Rotella straight 30 weight in my newly built 300 as recommended by the machine shop that did the work to mine...

I do not think the zinc issue only applies to newly rebuilt. I switched to diesel oil after replacing the cam in my mind-80's 300.

I use Amsoil for everything.....