Baron,
1, 3, and 4 are advice that you really would have wanted to follow if you owned a previous generation rotary. Older rotaries did burn a bit of oil but the RENESIS should be dramatically better in this respect than any other rotary from the past. I thought #4 was mentioned elsewhere as being in the owner's manual, but I don't have one to check. I don't see any harm in 1&3, since every previous rotary have had some issues with both. I suspect that because they moved the intake and exhaust ports they should both be non-issues, but if I were a new owner I would follow them for a bit just in case.

#2 - 5W20 oil is a pretty light oil. It's great for starting in the cold, and apparently helps with gas mileage very, very slightly. Many manufacturers are now recommending it so their CAFE goes up a bit.
I don't claim to fully understand this, so I'd probably recommend going with what Mazda says. However in *my* car, I wouldn't use 5w20 oil unless it was winter.

One other thing I will add, is that previous rotaries have been extremely sensitive to dirty oil. Since I push my cars pretty hard with plenty of redlining, stop and go traffic, and autocrossing and track days I always do 3k oil changes. The cost works out to a few hundred bucks over 100,000 miles, if I remember correctly, and I figure I'll be able to get that back when I sell the car. I know that I'd be willing to shell out an extra few hundred for a car with proof of 3k mile oil changes. I know that 5k-10k is fine for most people and most cars, but to me the idea that someone was that nuts about their oil changes says a lot about how they maintain the rest of their car. I figure that anyone who does that also keeps a good coat of wax on it, cleans off any salt during winter regularly, and does other general preventative maintenance.

JMHO.

 

I'm still not convinced that I should use a heavier oil than what is recommended in the owner's manual. There's been some discussion at http://www.rx8forum.com/showthread.php?s=&threadid=7675 that makes me wonder if the engineers might know something we don't. How about oil injection? That isn't a factor in piston engines.

 

Yep, that's why I said I'd probably recommend following the manual.

 

5W20 is used to improve fuel economy, that's it.

 

Being my second tankfull was 13 mpg, maybe it wouldn't be a bad idea to stay away from thicker oil.

 

13MPG ? Wow, I have seen 21MPG driving 80-90MPH. You must drive it pretty hard!

 

Let's just make it clear. Using 5w20 over 5w30 will NOT improve your fuel economy by even 1mpg. You need to think on a large scale here.. Multiply the very slightly increased mpg by thousands of cars and that's the CAFE benefit.

Also 5w20 and 5w30 will flow exactly the SAME in the winter since they are both a 5w oil. The first number is the "weight' of the oil at start up/cold temps. The second nubmer is the weight of the oil at operating temps.

I will not use a 20 weight oil in this engine, Mazda recommendations notwithstanding. I'll probably use Mobil 1 or Amsoil, 10w30 in the summer and 0w30 in the winter.

 

Hmm, that's kind of what I was thinking...both oils are capable of going down to 5W when cold, the 30W would do better in really hot weather though...

As far as points 1, 3, and 4 go (being true for older rotaries), I know what you mean. I still run into people who won't buy cars/trucks with aluminum engines, because GM was foolish enough to not use cast iron sleeves in the 70's Vegas or whatever, and now they think all aluminum motors are inherently bad.