I myself had a bad experience with the rotella in my duster when I had it. soon as I fired it up lifter noises scared me and the oil pressure went up to 80pounds I got afraid that I was going to blow the seals out the engine so drained it out and used 5 quarts of Castrol 10w40 with a bottle of STP and it quieted down I know everyone uses rotella 15w40 and have no problems . I'm just Leary about using it I have my 318 1973 valiant and I use Valvoline 10w40 with STP additive and it works but that engine is all original never been rebuilt what works for me may not work on others I live in north Carolina so I use 10w 40 if I was in Florida I would use 10w 50 . if I was in NY I would use 10w30 because of temperature and altitude this is just my experience of what I've experienced
