I have an SW cooler in the same position on my 6A with a 320. I never see anything over 185 in the summer, with CHT's in the 350 range.
First guess is a bad vernatherm or deformed seat on the case that the vernatherm tip goes into. ECI filter adapters are known to have issues aligning the vernatherm with the hole. Second guess and much less likely is a partially blocked cooler. When the vernatherm gets near 180, it closes the bypass, forcing the oil through the cooler. When they fail, they won't extend, or only partially extend, and oil doesn't flow through the cooler. Yours is likely partially closing, providing some cooling. This is a common failure.
If baffles were bad, you would see high CHTs as well and you are not
Baffle mount will typically perform better than one fed by a duct.
While 210 is beyond the normal range, you should have no issues with your oil, assuming a 35-50 hour drain interval. Oil does not seriously break down until 250-260. Don't recommend ignoring it, just indicating that you don't need to ground the plane.
RV-6A / IO-320, Flying as of 8/2015
RV-10 in progress
Last edited by lr172 : 06-12-2019 at 07:06 AM.