TCW3 vs. XD-100 E-Tec oil in older outboards
Here's a pretty good article
http://www.sea-doo.net/techarticles/oil/oil.htm
It explains that synthetic oils like XD-100 need higher temperatures to get rid of the ash on the exhaust stroke. Here's my question: anyone have experience running (and mixing, no oil injection) XD-100 in 1993 and earlier OMC motors, especially smaller ones at higher RPM?
I have friends who run XD-100 in the ca. 1993 V-6 (mixing oil and gas) at 9000 RPM. I've run it in my 1983 Johnson 35 @ 6100 RPM. With the cooler than standard Champion L2-G (I've got a bunch of them from 1985, but they're still made excepting the electrode isn't gold plated) the plugs ran slightly wet and the motor spit and missed in a strange way when I backed off the throttle fast (mixture is 37.5/1). With standard heat range L3-G/L77J4 the plugs run chocolate brown and dry. I don't idle much, so the question is whether to expect deposit buildup running wide open. With dry plugs I'd think not (I haven't pulled the head, the motor was rebuild recently). I worry about sticking pistons because I advance the spark to 33-34 degrees, but then run enough 110 Sunoco leaded along with pump 93 octane to get 95 octane fuel.
I'm wondering what to expect if I run XD-100 in our 1981 Evinrude 15 @ 6500 RPM (37.5/1 mix). The motor's in Germany, pump 95 octane is available.