What is the best synthetic oil?

Originally Posted by WarmAndSCSI

Actually engine wear is directly proportionate to engine load and RPM, so you'll find that UOA results vary a lot among the same exact car model. Unless everybody drives on the same routes, terrain, in the same climate, and with the same exact patterns and habits, then it's almost meaningless to compare UOA results apples-to-apples. That said, there are meaningful trends you can find among large numbers of UOA results...

When people start testing oils on our exact engine on an engine dyno with precise simulated load, I'll start paying attention to individual reports of empirical wear data. Until then, I'll stick with a proven synthetic oil which is first and foremost good on paper. The certifications tagged on quality synthetic oils are not just arbitrary - if you understand the parameters of each certification label, you can easily discern how "good" an oil is on paper. This certainly is a lot more scientific than using UOA results from a whole gamut of different operating conditions.

Somebody mentioned Pennzoil Ultra, which is certainly a good oil, and that it is Ferrari factory fill. This is not accurate - it's just the only American-made oil endorsed by Ferrari. i.e. it's the only American-made oil that has a particular formulation (5W-40 European car formula in this case) which meets Ferrari's oil specifications. Just like how only Mobil 1 0W-40 meets BMW's Long-Life oil specification. This doesn't necessarily mean it is factory fill from BMW...

The Pennzoil Ultra grade for our cars (5W-30, non European) actually has a fairly low HTHS rating of 3.1; which is lower than even Pennzoil Platinum. It's honestly not a very good high-performance oil. I would suspect it does clean very well, though, since that is what it's marketed to do best. But remember, Pennzoil Ultra 5W-30 does NOT meet Ferrari's specifications - it is not good enough to use in one of their engines, whereas 5W-40 European is. And it's not just the different base weight or weight split, it's the fact that the formulations are probably entirely different.

I've long been a proponent of Mobil 1 0W-40 since it is a very good TRUE synthetic oil (no Group III base stock is used in it). It has a HTHS rating of at least 3.5 and even though there are some reports of it quickly shearing to a 30-weight oil, it has proven to protect my own built engines very well. I've noticed hardly any difference in bearing wear when comparing M1 0W-40 to Red Line.

Currently, my pick for the 370Z is Castrol Syntec 0W-30 European car formula (made in Germany, AKA German Castrol). This is a true Group IV oil with an HTHS rating of 3.6 - it is very impressive on paper and has proven to protect very well over a broad range of UOA results. I only trust large, consistent trends in UOA results over multiple kinds of engines... that and the fact that an entire oil enthusiast community holds it in very high regard.

Originally Posted by Jordo!

How much is a lot? Would the mean wear still not be meaningful? But, even if so, for each given oil, there were as few as 1 sample and no more than 6 samples, so your point is very well taken...

Interestingly enough, some of the better performing oils from the averaged wear data in the oil nerd's thread included Castrol syntec (in both 0W30 and 5w30), Penzoil Platinum (not ultra -- can't recall if that was even tested), and Quaker Q state.

You gave two of those the nod, what are your thoughts on the Quaker state oil?

Oh, and where can you get the German Castrol?

Originally Posted by WarmAndSCSI

Mean wear is definitely useful; but most people tend to focus on the outliers (results from cars that are beat the hell out of, cars that are babied beyond all reason), which is just illogical.

Castrol Syntec is excellent stuff - 0W-30 is unbeatable for the price (~$7/qt). Pennzoil Platinum is a favorite of many and its real-world performance and specs on paper back it up - it's as good as Mobil 1 but generally cheaper.

Pennzoil and Quaker State are basically made from the same stock now since Shell owns them both. Shell Rotella, Pennzoil, Quaker State - all good synthetics, all made by Shell's SOPUS group.

I've never used Pennzoil Platinum, and never paid attention to when I used Quaker State Q or Horsepower of whatever the hell it was/is called.

You can pick up German Castrol at Auto Zone. It's been separate from the other Castrol oil every place I've been, and they usually have 5-10 quarts in stock. Make sure it says European Formula on the front and Made in Germany, only for sale in the Americas on the back. There are some unknown batches of US-made 0W-30 (circa 2002) still floating around, and those are to be avoided since they may very well be Group III-based and heavily packed with friction modifiers (much like some other cheaper 0W oils).

Mobil 1 0W-40 is also tip-top oil and can be used with our engines since it's essentially the same viscosity at every single temperature as Castrol Syntec 0W-30 is. Castrol 0W-30 is a "thick" 30 wt whereas Mobil 1 0W-40 is a "thin" 40 wt. They're roughly equals.

I'm digging German Castrol on the Z so far - dropped oil temperature 5-10 degrees from the stock average cruising temperature. Idle noise is the same as well, if not quieter.