unfortunately I've found no technical paper or analysis about synthetic oil
in REs.

One address with "product informations" is
http://www.royalpurpleconsumer.com/resources/faqs/rotary-engine/
but I think, you have seen it already.

In my old "papers on paper" (printed stuff) I've found a notice, that Mobil
One will keep stable up to 330°C / ~ 610 deg F. That was in 1995 ... (!)

And I've found the answer of Mazda by Yoshifumi Uneme in 1996. If have had
asked, why they do not recommend synthetic oil ... ;-)

Here's an extract of the letter, dated 1996/5/8 ...
"We do of course appreciate the advantages of the synthetic oil, and
actually have not set such a limitation for ordinary reciprocating engines.
For the rotary engine, however, we would like you to understand that we have
to recommend the exclusive use of the mineral oil for a structural reason
unique to the rotary engine; ingredients of the synthetic oil could swell
the internal rubber materials and thus affect the life of the rotary engine
in the course of time. To ensure the long and enjoyable motoring, we
recommend that you continue to use mineral oil for your RX-7."

Well, I've changed over to Mobil One + used it for perhaps 150.000 km (~
93.000 miles) or more - one of the best ideas, I've ever had ... ;-)

Do the "friendly men" at Mazda really think, that you will never find
additives in mineral oils, that will "hurt" their rubber seals ???
Especially mineral oils NEED a lot of additives, otherwise they will fail
...

In an old printed paper, published in 1973 by Goetze, they have tested IKA-3
+ Ferrotic for apex seals. They've found out, that lead in the fuel has a
big negative influence to the wear of the housing + the seals - it hinders
the oil film to build up fast enough, causing a lot of wear. And, of course
they noticed, that the oil film will break down, if you exceed the upper
temperature limit of the oil you are using ...

Ok, that's a "legacy" information - but still it's true ...

Perhaps you can ask the Mobil Company, whether they have some measurements
or test data ... ;-)

Frank Herfert

Thanks Frank.

I have been using Mobile 1 for as long as I can remember in all my cars.
I have had seven rotary powered cars since 1973. Still have a 2004 RX8.
A couple of rotaries went over 300,000 miles. Idemitsu rotary engine
oil is synthetic. Other than turbine engine oil it was the best of half a
dozen organic oils in a half hour bake test at 500 F.

Paul Lamar

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