Quaker State is an American brand of motor oil produced by SOPUS Products, a division of Royal Dutch Shell, and the successor of the Pennzoil-Quaker State Company. In 2002, Shell Oil Co., a wholly owned member of the Royal Dutch/Shell Group, acquired Pennzoil-Quaker State Co. for $1.8 billion in cash and $1.1 billion in debt.
A customer mentioned, "Quaker State's 5W30 engine oil literally made my car smoke. I took it out two weeks later went back to Mobil 1 no smoke. Don't believe the hype!"