is 20-50 to thick to run in a a 75 351?

[1BAD351 21]

I am curious because I know someone who runs it all year round. They run the amsoil 20-50 (I believe they stopped making that though and it is a 15-50 and that is what he runs now). I am trying to find a good oil to run in my 69 that won't wear my cam down; it's a 75 351w block though if that matters. I believe he said it has big oil galleys and it is ok to run, but in my experience that is a really thick oil to run in a street car. My engine has about 5k miles on it so everything is still pretty tight, its not old and worn out or anything. I also only drive the car in the summer time, it doesn't get driven in cold weather very often.

[rjardy 10]

It's weird...some guys swear by the heavy stuff and some guys say a 30 wgt. In my mind, it takes more effort to move a thicker oil through the motor. I break in with straight 30 wgt and run 10-30 after that. Never had a problem. But the heavier oil guys can make the same claim im sure.

 

Guess its personal preferance.

[1BAD351 21]

yeah I always felt it was to thick, I feel like anything over 40 is to thick, but that is really based on my gut, I have no proof either way.

[rjardy 10]

yeah, neither do I other than I have never had one grenade on me.

[coz 108]

I run 10W40 in the winter and 15W50 in the summer. Either would probably work year round. I think 10W30 is too thin. 20 and 30 weight oils are really geared to the newer, tighter tolerance engines.

 

One thing I did read about thicker oils is they create more block heat (not much but some).

[bnickel 10,004]

i run 20W-50 castrol all year round in all my cars, except the wife's 02 escape and i run 10w-40 in it all year round.

 

i believe the original recommended oil for the 69 351w was actually either 20w-40 or 15w-50 so the 20w-50 seems a perfect oil to me. once i build my new roller motor for the cougar i'll probably go down to a 10w-40 but i may stay with the 20w-50

[1BAD351 21]

ok cool, thanks guys, amsoil 15-50 it is:cool2: