They do have the grease for $3.49. There's a couple different Arctic Silver's, the Arctiv Silver 5 seems to be the best. The cost is $12.99 but I'm not worried about the cost. I just want the best product to dissipate heat from the plug to the engine case.
I would buy the Wacker P12 that Rotax suggests if I could find it. But there is some logic to what you said earlier about it probably being easier to get in Europe.
I'll try the RS Arctic Silver 5. I need it this week as I am hoping to reassemble my bird from winter storage and I want to change the plugs while the wings are off.
Thanks to everyone for all your help.
Mike