New XPS oil, 100LL and decalin

I'd  still use it because it's in the fuel and not in the oil.

Roger Lee wrote:

I'd  still use it because it's in the fuel and not in the oil.

Interesting, though, that Rotax removed the mildly positive statement about Decalin. Now it says, regarding Decalin, "...no data exists from internal qualification programs to validate their effectiveness or long-term effects on engine operation. The use of any untested additive is at the sole risk of the operator, and in the event of engine issues with a proven causal link to such additives, warranty coverage may be denied."

Sure seems to be a change of tune!

Mike...the statement they make is correct.  Rotax has now accepted that XPS as approved for all the aircraft version engines.  That said XPS has told the users that they should not use any additives, this includes Decalin.  The base formula is not the same as Shell as an example.  Given there has been no factory testing any user must then accept the risk of an oil to additive conflict.  

Cheers

Why would Decalin be an issue since it is a fuel additive and shouldn't directly affect the oil itself?

Hi Roger.  

The oil will pick up the Decalin in the combustion process, just like it does with Pb, Lead.  The XPS was especially formulated to work with 100LL fuel and scavenge lead so the Decalin can conflict with the base oil.  This is what the XPS engineers have told us in presentations when the oil was introduced.  

Cheers