quote:
Originally posted by sands:
SNIP
This begs the question...Are all Group III oils the same quality ? Are all POA base oils of the same quality ?
This may be a starting point for finding the best oils ?
I'm reasonably certain not all Group I, II, III, POA or PAO oils are the same.
There are an almost infinite number of ways to refine or synthesize the oils, and we know that not all blenders do things the same way.
I know for a fact that Castrol's process for making their Group III (XHVI, I think) is proprietary, and more expensive than some other Group III processes.
Reagarding your last sentence, I think that the way to find the best oils must be one of the following:
1. Wear checks based on testing. We (the BITOG members) probably can't do this enough under controlled enough situations with a large enough sample size to be effective.
2. Comparative statistics of oil-related based on a wide sample of vehicles with different oils in. Due to the rarity of oil failures outside of about 7 different modern cars I can think of, I doubt we'll ever build a good database for that.
3. Used oil analysis. We probably can't get a statistically valid sample, but we can build a LITTLE bit of confidence with enough samples for at least a few oils. For instance, we probably have enough UOAs of Mobil 1 or GC to reach *some* conclusions. For other oils, like Kendall or Mystik, we have as little as one UOA per grade, and we'll never really get a clue as to whether those oils are good or bad or indifferent.
The great part about the API, ILSAC and ACEA standards is that at least we can be guaranteed of certain traits from oils that meet them. I know any ACEA A3 oil will handle as much heat as *I'll* ever throw at it. I know any API SM oil will probably not kill my car's cat.
Also, regarding us paying too much attention to adds, and not enough to base oils, I think you're probably right. We see oils with add packs that LOOK really skinny turn out perfectly good analysis, and oils with very high additive numbers turn out analysis that isn't much better.