Crazee D said:
Thank you for the excellent summary goldy!
So if I can pick your brain a little further for the benefit of myself and others...
Of the types you mention, which are better engineered for what applications?
Turbo or N/A, cold/hot climates, daily driver, etc..?
To first answer your question: it doesn't matter. The best oil is the best oil, period. The only thing you should change between Turbo/NA, hot/cold, etc is viscosity.
The simple fact is that you drive a mazda that puts out under 300hp. You will never fully utilize the full potential of synthetic oil; and honestly, the only benefits you will see between brands is the cost and availability of each. To anyone who disagrees, prove me wrong. If your car is making 200hp and you switch between synthetic oils, you will still be at 200hp. Any variations, for better or for worse, are due to other variable conditions under which you have little to no control. If you car regularly maintained, switching between synthetic oils won't make it last another year/15,000 miles. Period.
I did research on this subject EXTENSIVELY two years ago - to the point where I did individual oil analysis tests for each brand of oil using applications from a 2002 Honda CR-V, a 2000 Grand Prix GT, and a 350whp '73 Dodge Charger. What did the study conclude? It concluded that differences between oils were within % errors that could have been due to other factors (engine wear, humidity, switching oil filters, air density, air temperature).
Most of your benefits will be simply due to the fact that you switched to synthetic and you stop using a low quality oil filter. Changing synthetic oil under 5-6000 miles is a waste of money unless you are pushing huge power numbers, AND your driving style mimics a drag strip (eg, drag cars).
I found the best oil change intervals for the GP were 6500 miles, with a filter change every 3k. The CRV did significantly better at 9k and two filter changes, and the charger needed to be changed every 4k miles with filter. These were with Royal Purple (the best intervals for filter changes were actually higher, but still less than oil change intervals)
Separate oils were only tested in the GP and Charger. Both times, Red Line won with overall performance. The owner of the now-sold Charger (my best friend) still uses Red Line in his Duster. Amsoil fared the best for oil change intervals - their advertisements are nearly true. After 10k miles on the GP (and a very scared owner..me) the oil appeared good to use for another ~5k miles. Our Mazdas could probably afford 7-8k miles with filter changes half way. Anything less than 6k miles would be a waste of money, and you are better off sticking with dino oil.
The reason my friend and I both used Royal Purple in our daily drivers is because it was the cheapest for us to buy in bulk - MUCH cheaper. Considering it fared almost as good as both Red Line and Amsoil, the economic gain by changing the oil in somewhat shorter intervals outweighed paying the extra cost for Amsoil and Red Line - despite their SLIGHTLY improved performances.
Go to bobistheoilguy.com for a starting point for your search for the "best oil" and "best filter." Either way, you will not be able to tell a difference between the best oils. Period.