Be advised, according to the API (American Petroleum Institute), if an oil contains ANY synthetic oil it can be labeled and sold as a "full synthetic".

A full synthetic is made entirely of group IV base stocks, as opposed to a mix of II, III & IV.

If you want the best oil, forget the laughable API starburst and/or the ILSAC designations. An ACEA A2/B2 (or above) is an excellent choice for most vehicles unless your engine specifically requires a different designation.

You also need to read the label very carefully. For example, "Meets or exceeds GM4718 for engine protection" actually means it failed to meet the GM4718 specification. Engine protection is only 1 criterion on which the GM4718 spec is tested on, so unless it states on the bottle "Meets or exceeds GM4718", it failed. (I'm using the GM4718 spec because it's the only one I can remember off hand).

Also, all oils are not created equal. Believe it or not, some 5W30's are actually thicker than 10W30's at operating temperature; and if you're using bulk oil, forget it. Drum oil is notoriously cheap and low quality, passing their lubrication tests by the use of additives which break down quickly once used in an engine.

I could drone on and on about this, or you could go to motor age magazine online and search for some articles by Kevin McCartney, a noted tribologist.

Unfortunately, most of the info I have on oil properties/qualities comes from an industry site, iATN.net, which doesn't allow sharing of content.

It's also important to note that oil isn't just oil. Typical dyno oil is about 75% oil and 25% additives, which do wear out. Once those go, the actual protection properties of your oil plummet.

If you really want to know what's going on inside your engine (and how often you need to change your quality oil), check out blackstone-labs.com. You might find that with the correct oil you can go from changing once every 5k miles to double or even triple that, according to your engine health and driving habits.

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A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.