Burla, you seem to be the oil expert on this forum, I have a question. I have a 2011 hemi Ram with 109,000 miles on it. Am using 2qts of PUP 5/20 and 5 quarts of PUP 5/30 for summer and opposite for winter. I have light piston slap when really cold. I also use bio lube and change oil every 4,200-5,000 miles. Do you think It would be better to run 0/20 or 0/30 in the winter with moly additive. Have been using moly for last 80,000 miles. Thanks for your help.
I like PUP a lot, use it in my other vehicle and if not for hemi tick I would likely be using it in the ram, and it has earned the top spot for the most popular oil on the forum. I know the 0w20 has dexos spec, but that is it for the stay in grade desirable specs. My guess and that is all I have "a guess", is that GtL base oil allows them to make this spec, when other oils such as m1 need to add base oils like pao to meet this spec. I believe for the cold pao is the better option then GtL, pao even beats esters in cold performance.
I would not be afraid of 0w20, especially seeing most of the good ones carry the desirable stay in grade specs. But I would "try" to find a year round oil I didn't have to mix. M1 is the safe choice, they make 0w30's that are top shelf. But, if 0w30 still gave you cold piston slap, 0w20 m1 is worth a try. It isn't scientific yes I know, but if you watch those cold flow -22f m1 rocks those tests. Consistently and in nearly every one of those I have watched the m1 is the clear winner if we exclude redline.
If you want to stay with PUP, by all means try 0w30 and see if it helps, it might just help. Now,
here is a link for you to consider, and mind you most of the cold performance info I receive is second hand from guys here that live in the snow states. So another strategy for you to consider is find the oil with the best CCS numbers (cold crank viscosity) and give that a try. I believe a ram forum member has done this and it wasn't m1, redline or PUP. I forget which one it was to be honest.
It likely will be trial and error for you, but I believe it is a worth while task, and don't be afraid to walk a way from brand if it isn't helping. You are now armed with some good info and a starting point. Do us a favor and let the syn thread know if you were able to solve this and what oil helped.
I would be considering oil filters as well, sometimes the right oil filter is just as important. Maybe the 10-48 is better then the 20-820, I simply do not know the answer here. Also, from other guys in cold states like hemi395 and u&a, fill sump 1/2 quart over fill line.
