I run sidewinder 20%-12% in all my trucks with no problems. My 18SS runs fine on it, When I said it was hot, I just meant it runs hotter than what I AM USED to. Plus my temp gun might be a little screwy too!!! I am starting to just say "forget temps" and tune according to sound and smoke.
When I raced it last night with the OS 18CVR in it, the highest temp was 247 and my Revo with the 18TM in it only hit 217 but they both ran very well and I probably should have been running the TM a little richer as it had a little too much power for my driving style and track we were at.
The unfortunate thing is that everyone has there ideas and thoughts regarding what temps are best for an engine....All these R/C companys are in California or Texas where there weather is totally different than other peoples...I have called Traxxas and HPI both and I always hear the same thing from them....The temps are a tuning GUIDE!!! and that is it, Traxxas actually told me to throw away my temp gun. LOL. Dont get me wrong though I certainly wouldnt want to see any engine reach 500 degrees or something like that, But if the engine is pulling good power, has lots of smoke and sounds the way a nitro engine should then it should be just fine.
Once again though, that is just my experience, I am sure some may agree and some may dissagree with it, But everyone has there own ideas and thoughts. What might work for me, may not work for someone else.