I used the model lube http://www.klotzlube.com/proddetail....0%5FPint&cat=8
in my D+B 3.7 twin for aprox. 10 years mixed at 50:1, never a problem, never changed plugs,
7500rpm on a bolly 21X12, aprox. 50 gals., crashed airplane several months ago and bent[]
crankshaft, took apart to inspect, engine LN inside.

I just switched to Stihl Ultra synthetic because I can get local. Klots I had to order, so far 4 gal in
my 7yr old 3W75, runs great!!