Originally Posted by Pinoak
I would go with a thicker conventional in your situation.
Unless something has changed, those rotary engines need to, by design, burn oil. The modern resource conserving and now sn+ oils are Said to be blends. Synthetic dosent burn off easily enough.
Now I had an 87 rx7 and that was a long time ago. Maybe things are different now.
I believe the deal is that by design the engine sprays a little bit of oil into the seals to lubricate them, which then has to then evaporate off cleanly or will leave deposits.
But the real question isn't really about synthetic oil, but about whether or not a particular oil will burn off without leaving deposits in those seals. I remember hearing that recommendation against "synthetic oil" in a rotary back in the 90s, but "synthetic oil" is far different in 2019 than it was in 1996. Is there really any blanket recommendation that would work? I'd think it's really a case where a slight formulation change (which wouldn't likely consider the effect on rotary engines) could mean an oil that burns clean could become one that later leaves deposits.
Idemitsu actually sells a rotary-specific PAO/ester based "synthetic oil". They claim that it's designed to minimize deposits. It's not an API certified oil, but they claim it exceeds API SM specs.
Quote
http://www.idemitsu-usa.com/h/39/10w30.htm
- With the precise base oil mix of PolyAlphaOlephins and PolyEsters, Idemitsu Rotary Engine Oils are able to minimize those deposits on your apex seals.
- Allows for better sealing of the chamber, facilitating more power generation.
- Extends the life of turbochargers by reducing bearing coking.
- Specially developed additives facilitate even tooth load on the front stationary gear to allow for higher loads and higher RPM.
- Premium anti-wear agents create a strong film between the main bearings and the eccentric shaft, reducing metal-to-metal contact and minimizing bearing wear.
- Developed to reduce entrained gas generation. Entrained gases reduce the oils ability to prevent metal-on-metal contact, thereby increasing main bearing wear.
- Includes Molybdenum as a friction modifier. This compound reacts with the metal surfaces to create a low-shear boundary. The low shear characteristic reduces friction, increasing efficiency and power output.
![[Linked Image]](http://4imgs.com/1086/sys/add/1/10W30.gif "[Linked Image]")
Not sure where to find this though. All I can find are sellers on eBay. They also have a 20W-50 version. And changing this every 3000 miles would really hurt the wallet.
