The trailtech temperature gauge is available with different sensors (
https://www.trailtech.net/tto-1)– at the spark plug or for coolant (for detail see
viewtopic.php?f=20&t=359 ). Available is also a PT1/8 sensor and with a M12x1,5 to 1/8’’ reduction it fits instead of the oil plug.
32C ° outside temperature - time for a summer test. The trailtech gauge shows the oil temperature, the Acewell speedo the coolant temperature. After 20km at max 110km / h the oil temperature was at 81C °. After another 20km full throttle at 93C ° (see picture). This was the highest measured value ever. The oil temperature dropped significantly when driving around town, even on slow dirt roads - generally it remained at a little over 80 ° C and thus significantly below the cooling water temperature. Actually surprising. So I guess even in summer oil temperature is not an issue with the NX250 engine.
A different issue occurs at colder weather. For instance, at
15C ° outside temperature after 10km at slow pace the oil temperature did not even reach 50C °. But then I had enough of the loafing and went on the gas. After another 10km at 110km / h the oil temperature was at 67C ° (coolant 78C °), after another 20km with 120km / h oil 75C ° (water 85C °). After a few km of country road, however, the temperature dropped below 70C°(see picture). That could be a problem – the motor oil is not getting hot enough to get rid of the condensation water. That is probably the reason that the engine guard of the NX250 does not have a single ventilation hole - it’s totally closed in order to prevent loosing too much heat.
Since my NX is my winter bike I went back to the origional engine cover