Quaker State, Castrol Syntec, Valvoline, Pennzoil and several others are only Group 3 synthetics (Carbon Based with Parafin)
AMSoil, Redline, Royal Purple and Mobil 1 are Group 4 synthetics (PAO based created in the lab)
I think that Redline is actually Group 5.
Group 3 oils are good quality, but not the same level as the Group 4 oils.
I am running Mobil 1 in the 04 Tundra because it is easy to get.
Full Synthetic and Blend leak in my 85
