I think that some information presented in this post might be very controversial or simply wrong. However, I can’t be silent reading your discussions about advantages and downsides of engine oils.
I see a lot of experience and knowledge behind most of the posts. As well we can see many lab conclusions, analysis, test results, objective, and subjective oil ratings. I’m sure all posts have some ground to back this information up; otherwise you wouldn’t post information (hopefully).
My opinion – there is no way you can find the best oil for your engine, or gearbox, or differential. All information presented in test and labs quite far from reality. It is certainly biased, unless tested by independent government organization with no knowledge which brand or grade is it beforehand.
But the real problems are driving conditions. There are too many variables to consider. Factors like engine type, operating temp, how well it was maintained, outside temp, driving style, humidity, etc. etc. must be taken into consideration. One type of oil might be good for one type of car and driving conditions, other oil can perform better for other car.
There is no way, I suppose, to see what is the wear for the specific engine unless you take absolutely same cars put them in a gear and run at 5000 rpm for 6 (or more) months with recommended oil changes, or maybe extending drain interval. After the test disassemble both engines, transmissions, and etc. and compare their wear values. I think only in this case you can tell which oil protects better and offer less wear numbers for conditions similar to test. You can also compare fuel economy, oil analysis and make some conclusions base on them.
Also organizations must take into consideration cost-benefit analysis. Is it worth to put in fleet engines synthetics at cost 4 times higher compared to regular oils? If synthetic can provide extra 20,000 miles to the engine does it really matter for commercial engine with half a million miles already on it? Or is it just simpler to throw it away and buy a new track?
If I am wrong, please indicate my mistakes and misunderstanding so I can extend my knowledge of lubricants, their effects and properties.
Thank you,