Originally Posted By: Johnny
If you are going by sales, Pennzoil by a good margin. Pennzoil has been the number one selling PCMO in the USA since 1985. The last sales report I saw, which was back in December had them ranked by sales volume, Pennzoil, Quaker State, Valvoline, Castrol, then all the rest.
To give you an idea of how much Pennzoil is sold every year, the volume exceeds both Quaker State and Valvoline put together.
I'm surprised that Valvoline is 3rd on the list. Seems like Castrol would outsell Valvoline.
In general, I like Valvoline better than Castrol. Castrol is overhyped.