I personally use (and yes sell) Archer Pertoleum Products. This isn't an ad for Archer, they sell mostly to farmers, ranchers, and industrial contracts but I feel I can help out here. I try to stay out of all posts involving oil, my opinions are biased twards Archer and I would rather not start anything here. I think it is good that there is so much intereast in the oil analysis, and that people are trying to disprove the myths of when to change oil. The only way to really know when to change your oil is by analysis, all oils are different and they will break down at different rates. There are many different variables such as engine condition, and driving style to name a couple. Synthetic oil doesn't break down as fast as conventional oil but it does get contaminated just as fast. As soon as an oil gets contaminated it is useless. Oil may last 10,000 miles in one vehicle but only 4,000 in somebody elses identical vehicle. For example, I have found out through oil analysis that oil can only go about 3000 miles befor it becomes to contaminated (due to fourwheeling and overall poor condition of my engine) so I use 10W30 conventional oil. The oil in my Neon however can go about 8000 befor being to contaminated, so I use 10W30 syntheric. I should also point out that the oil still isn't broke down very far at this piont, just overly contaminated. I know vehicles that go 12,000 miles between oil changes.
The point I am trying to make here is that what is good for one may not be good for others. The only real way to know what will work for your engine is to establish a good oil management program. I personally have analysis done every other oil change, so I can keep an eye on my engine. It is free for me (and anyone using Archer products). As for which brand to use, pick one with a good base oil and minimal additives (79 cent Wal Mart oil isn't a good oil.) An oil with too much additive is its own worst enemy. I can prvide anyone intereasted analysis breakdown for most any brand oil both synthetic and conventional but as I said befor the only true way to know is by having YOUR oil analyzed.
This has gotten long enough. I am open for any questions or comments (good or bad).
JAY