Which 15w50 did you use?
Mobil1 was the only I could find in town that wasnt either a house brand or some ungodly priced synthetic from summit racing. I cannot attest to it being good oil or not, but in the heat on long drives I do like having a few extra psi. I really want to get some schaeffers ordered before winter time comes because I put ALOT of miles on in hunting season. But Ill just order standard weight oil for the winter time.