My Boxster says to use mobil 1 but....

[boxster_s_boy_34]

Here is the break down of synthetic oil as I understand it. You have 5 classes of synthetic oil. The first 2 classes of oil are conventional oil that has been Hydracracked ( realigning of the oils molecules to make it better and more durable) with a synthetic addative to aid in burning and breakdown. The next 2 classes, 3 and 4, are also Hydracracked with more addative in them (not sure of percentages) to make them even better yet. The last class of synthetic oil, class 5, is a true fully lab made synthetic. The only oils that I'm aware of that are class 5 are Redline, AMS oil (short for ametures oil in my opinion), Torco t4-r and straight weight Mobil race oil. Mobil 1 is a class 2 at best. I personally use Royal Purple which is a class 4 because it is affordable ($9 a quart) and gives plenty of protection in my eyes. I cannot justify $15 a quart for some of the class 5 oils that are out there.

[jim_hoyland]

Interesting information about the 5 classes, never knew that. What class would Swepco 306 be ?

And, how can one tell which class an oil belongs to from looking at the container ?