I run 20-50 in my 69

 

I have run 20/50 in mine forever. No oil cooler either. I do have solid lifters, if you have hydraulics and they are in good shape you should not have a problem.

 

Thanks for all the info guys,the 25/60 castrol seems to be doing well.I think i will change the # 30 that i have in the primary at the moment to TDF,neutrol is a big hard to find. Thanks Harbri