Imho, the oil itself won't make a ton of difference on the cooling itself, but better oils will certainly hold up better.
One of the best things you can do is to make sure your stock cooler, which I believe is a 6 row Jag, is working efficiently. I just removed mine after inspecting it and noticing that alot of the fins were clogged. it's very hard to see unless you turn the front wheel and really get in there and look closely.
When I could finally hold it up to the light, I could see that almost 75% of the fins were clogged with debris, mostly tiny little pebbles and cottonwood fuzzies. Took a .020 finger gauge and ground down the edges so it just fit the gap and I went one by one cleaning the gap and straightening each fin. That helped tremendously in the stop and go in Sturgis. Before it would get up to 270+ and start idling down to 600 and was really struggling.