I changed my oil today. Before I was using 10W/40 (for winter and all, although 10W/50 would have been a better bet), and now I switched to 20W/50. After I finished with the change, I went out for a drive, and I noticed that the car behaved a bit differently. At idle, the engine/exhaust note seemed a bit lower and deeper. Also, I felt that it had a bit more power all through the rev range. Recently, the weather changed from about 50ºF to about 75ºF. Could change in oil actually make a difference in performance, or am I simply imagining things?

Also, has anybody had any experience with Royal Purple synthetic oils? They're supposed to reduce internal friction and give you some BS +2% power. Just wondering.

 

most better synthetics (royal purple, redline, amsoil, neo, mobil1) will provide about a 1% increase in HP.

 

That's not bad, considering it's just a few extra bucks.

 

I've been told to avoid synthetics because they leave residue behind after the rotary burns the oil.

 

Yeah, the owner's manual says to never use synthetic oil, but Racing Beat has been reccomending the use of modern synthetic oils for a couple of years now, so I think I might give a synthetic oil a shot after 2500 more miles.

 

ah man, do we have to shave the barber again???

You may wish to use the search function found in the upper right hand corner of the page to search for the countless threads already discussing this.

Again (as posted a billion times on this board) better quality synthetics (as mentioned in my reply above) are perfectly fine to use in a rotary engine. In many cases, they burn cleaner, and leave less ash and other residue than most conventional motor oils.

It is the poor quality synthetics like the Castrol Syntec or Valvoline ones that you want to stay away from and not use in a rotary because of the higher ash content and other issues.

But now Mazda couldn't quite say, "you can use Castrol 20W50, but don't use Castrol Syntec" in the manuals could they???

Or they couldn't say, its fine to use Amsoil synthetic but not Valvoline synthetic.

So they simply just said don't use any.

But in the 25 years of RX-7s and 34 years of rotary engines in production cars in the USA, we have learned that a good quality synthetic is perfectly fine and will only increase engine life, provide slightly more power, and a smaller wallet as the only side effects.