Brendan: when I was stationed in the "U/P" I ran 10-30 in my 58 Impala with 348/3duces. It was a little slow starting (battery) on the coldest days but otherwise no problems but I was only there for a year. It depends a lot on "Cold engine" ..."Hot Engine" as they both need different attention at at different times. I would think that engine oil had changed due to the CLOSER TOLERANCES(?) now used on most engines but I say that cautiously!! I know a LOT of folks in my warmer climate run SAE 30 year round, and some that run the multigrades and none have problems. I think any good grade will do good if vehicle is maintained regularly. During my life I have sworn by Quaker State, then Pennzoil, at one time I was a Shell Single G man, but for the past 30 years its been Valvoline or Castrol. Valvoline in HP engines and Castrol 10-30 for daily drivers. Heck. I remember years ago that I swore by Wolfs Head if any of you remember it. So, take your pick and good luck. I would heed the advice on the flat tappet lifters/cam's. I would also be careful as mentioned above on the Rotella until I knew for sure! Post #7 of 50
