I got this guide also. However talking to a couple of rotary nuts/machanic friends of mine they say it can't hurt using synthetic, but if you change the oil every 3000....save yourself some dough and use non-synthetic.....if you are really burning a lot of oil, becuase you live at the redline ;-), you may want to give synthetic a try. It is not likely it will hurt the engine.

I use non-synthetic but mostly because I am cheap!!!!! and I am leasing my car so I won't have it past 60K miles anyways.

 

That driver's guide mentions adding oil to your rotary as it is spent.

One could argue that because most (if not all) of the dealers are using dino, that is what you should use to top off the engine. In other words, they could be saying don't mix and match more than they are saying don't use synthetic.

Other Mazda reps on this forum have said synthetic is fine.

-Mr. Wigggles

 

This is straight from the horses mouth..............

In regard to using synthetic oil, Mazda does not test any of our
vehicles using synthetic oil. As such, we do not recommend the use of
synthetic oil, only because we have not tested it.

Also, I found out the folder you're inquiring about is the Mazda Driver's Guide, part number 9999-92-rx8d2-04
. The Mazda Driver's Guide is intended for
the sales staff at the dealerships to learn about the RX-8. However,
Mazda is currently in the process of revising a guide for customer
use. We are hoping to have a revised copy available to customers within
the next couple of months. Testing with synthetic oil is now taking place

I hope this information is helpful for you.

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Regards,

Lisa Lasky
Specialist, Customer Assistance E-Business

 

Lisa,
I hope that your comment refers only to the US market. In Europe the oil that is intalled ( if that is the word ) at day one is synthetic.

I do hope that somewhere in Mazda somebody had tested this oil.