http://download.aopa.org/epilot/2008/081125exxon.pdf (dated 2008)

Seems an odd position to take. The pursuit of a certified diesel single is still underway though, so the manufacturing giant Cessna must seem confident that this isn't a factor?

Doesn't make them as much money. So why would they want to do that! It made it clear they don't want them to use jet A on an engine that should be "piston/100LL" Powered!

I sent that letter to a friend of mine who is an aviation lubricants expert at Shell, and here's what he had to say.

"Interesting, Shell is in full swing in support of diesel aviation engines both from a fuel and lubrication perspective. We are currently testing multiple engine oils in Europe with the folks that bought Thielert??"