Paul--

This may be an off the wall question; however,--since 1/3 of the cooling
for the 13B is accomplished by the oil and the rest by the coolant in
the radiator and side seal of the rotor integrity is of paramount
concern, why not try putting motor oil in both the crankcase and the
"coolant system"? Oil is lighter than water.

Tom Chapman

Side water seals are no longer a problem. Particularly if you
use Teflon encapsulated silicone O-rings. Oil is not a good
coolant fluid. The heat transfer from oil to metal is not
good. I suspect it has something to do with viscosity. Bill
Schertz on here is our resident expert on this subject.

Pure water is best. Everything else is downhill from there.