Since Amsoil motor oil is less likely to thicken ... based motor oils may be considered niche for the casual consumer. Pennzoil produces a range of conventional motor oils, synthetic blends ...

As for the best oil brand, Ram and Chrysler owners swear upon the efficacy of 5W-20 fully synthetic motor oils from Pennzoil, Mobil, Amsoil, Redline, Fram, and Royal Purple. Any brand is suitable ...