I'm not going to argue, but all three, Pennzoil, Quaker State, and Shell Helix Ultra, have top shelf oils with a base oil made from natural gas with, yes, slightly different additives depending on application, such as "Euro". In my previous reply I said their "top oils" and "essentially the same". Cleaner than those, such as mobile 1, which have base oils made from crude as are lower grade Pennzoil, Quaker State and Shell oils which are petroleum based. All three natural gas derived oils are good oils, and my preference, as stated already, is Pennzoil Platinum Euro which has a 15 year, 500,000 mile, whichever comes first guarantee. I prefer to use the Pennzoil Platinum Euro additives for a European engine such as a MB Crossfire engine as opposed to Pennzoil Platinum Ultra which is also a fine oil but without the Euro designation. The Euro additives are made to protect for longer intervals between oil changes, and European engines are made for longer intervals (7,000 miles vs 5,000 miles). That means American engine oil formulations have additives that likely wear out sooner since they're not made to last as long. I prefer that my additives last, even if I change sooner than the 7,000 mile European standard. As I also already stated, all three meet MB 226.5, 229.3, and 229.5 standards. You use whatever you like, which you stated was Quaker State Euro, a fine oil. Ok? Ok.

The oils are essentially the same except for POUR POINT, which likely are the same all else considered.