Todd, I wouldn’t worry too much about cold oil as long as it is 100% synthetic.

I’m near Ottawa, so it can be +30C in the summer and -30C in the winter with significant temperature swings from day to day.  At one time I wanted an oil cooler thermostat for winter flying, as I was scavenging heat from one oil cooler (I have 2) but have typically opted for air flow restriction.  I was restricting one cooler (Fluidyne) at < 10C and both at < 0C; historically I had better oil cooling than water jacket cooling but last summer I decided to try increasing the water cooling at the expense of oil cooling.  One of the Fluidynes was converted to a large “heater core” and feed from the  3/4 inch port designed for that; the result was cool water and hot oil.  I then bought a medium sized Mishimoto cooler through Amazon and went back to 2 oil coolers, though slightly less capacity than before.  The result is now I have pretty well matched temperatures throughout the power envelope.  The other day cruising at 2500 ft and 27C (80F) both temps settled in around 177F ... I’m okay with that because at 32C my temps should both be under 190F.

This past winter I decided to try out a thermostat on the water jacket because without it the water temps would barely register (110F) if OAT was near freezing and I now have a big “heater core”.  The result was my water jacket temperature was between 185F-190F all winter long (better cabin heat) and my oil temperature was typically around 175F-180F even on cold days.  At present I’m operating without any thermostats but around November I’ll put the water jacket thermostat back in ...

Jeff

 

Some (most?) Of you are using custom or at least aftermarket oil coolers but I think there are a few like me that are using stock oil coolers. How many have removed the thermostat and plugged the bypass hole?

Do any of the non-stock coolers have a thermostat? 

A Google search on the subject shows that on the RX7 forums it seems to be generally accepted to leave it alone.

  But for our use I'm less inclined to think we always need it and it seems to be quite restrictive. 

  Of those flying without one in either stock or non-stock, how many are flying in warm climates only? Anybody in cold? Jeff? 

  I'm just concerned about winter flying especially during a long descent where it might cool excessively and then if I was required to use sudden power for a missed approach, would that cold oil be a problem? 

 

Todd