Hot is relative...More oil won't make it run much cooler, if at all...
How hot is it ? You can't check it after idling around after landing, only way to tell is with an in flight temp sensor mounted under the spark plug, and a way to read it out...
300F is not too hot when running at WOT...
TOO hot is when the piston sticks in the cylinder
My engines routinely run at over 300F on the test stand, drop almost instantly when idled down...