Originally posted by Big Jim:
Pennzoil and Quaker State are most nearly the same product. They came together long before Shell bought them. They use the same base stock as Chevron dino oil which is really as much of a synthetic as Castrol synthetic.

Chevron and Havoline (Texaco) are very nearly the same product and both use Chevron's "iso syn" base stock.

Mobil Drive Clean also uses base stock that is nearly synthetic. The latest GF4 formulation actually uses a slightly better base stock than Chevron (group III from Mobil vs Group II+ for the others). Mobil also supplies GM Goodwrench oil as well as Chrysler Mopar oil, which are probably also very nearly the same oil.

Conoco, Phillips, Union 76, Kendall, and Motorcraft are also very nearly the same oil. They also use Chevron's "iso syn" base stock. Motorcraft actually labels theirs as "synthetic blend".

I don't know much about Valvoline.

Of the ones you listed, I would choose Havoline (Texaco), but there isn't that much difference between any of the ones I listed to make it a hard fast choice.



Can you document this information?