Once again...testing on a OLD vehicle, you or whoever decided to do that, prob had about 100,000 miles of DINO oil through it. At that point, WHY do you think switching would make a difference? You would already have deposit buildups, and on top of that if you've been running dino forever SYNTHETIC can have an effect on the seals. On top of that an old engine like that was made to run tride and true on dino, and could handle oil sludge problems with a breeze. Engines on the FJ, (1GR-FE) are far more sensitive, as anyone who has ever worked on the engine can tell you. Do a test on the FJ, use REGULAR dino, then SYNTHETIC, you SHOULD\WILL notice smoother idleing, smoother cold-starts due to the better low and high temperature viscosity performance, and down the road you'll see that you should have no, if any, oil sludge problems. And the the fact that synthetic oil breaks down so much slower and is so much better in winter weather than dino (which can freeze) it's just a win win with new engines. A great vehicle to see the difference on if you REALLY wanna feel it, would be BMW's M3 (07), it runs poor as hell with Dino, and the engine just chugs along as it doesn't handle thick oil very well.
Anyway, I'm done, RP worked for me, I felt and saw the differences on the scanguage. If you want to a right test, do it on the vehicle on discussion. Using a high-grade synthetic on a vehicle that has been using dino for ages just doesn't make sense and isn't going to give you the benefits. That's like buying a truck that requires 87 fuel, and putting 93 in it. You wont tell a difference, and it MIGHT mess it up a bit. Where as the FJ can RUN 87, but works far better, and runs smoother, with 93. Same thing with synthetic oils in the sucker, it just runs smoother with it.
Oh, and only ONE link you posted worked. However, I did enough studying of synthetic oils before I switched my baby over to it, so I have no need to read them.
If we are gonna be posting links, then here's dyno list of RP.
Royal Purple Summary of Independent Tests
BTW, I am NOT trying to bash you or disprove you, I know for a fact on old cars\older cars synthetic shows no benefits, such as my friends Tahoe, he had 100k of dino run through it, and synthetic didn't even make a slight difference. all I'm saying is I believe in synthetic oil in newer engines, and I have personally seen the difference...that's all. So I WILL recommend it to people, at least on the FJ Cruiser, and you WILL see the benefits down the road when you have no sludge build up, and you're engine has been fully protected during cold-starts, and the lower temperature during hard\long driving.