After picking my bike up in Bishop, CA, I set off north on 395, stopping a few times to take some pics before heading into the high desert. Bishop was at 97F at the time and as I rode farther north (and up), I felt it getting warmer, my guess at least 5 degrees. Looking down at the instruments, couldn't tell anything because of the bright sun. Quick hand shade reviled the warning light on (don't know for how long). This happened once before (98F day) and as I slowed and pulled over, the light went out. This time it didn't. I shut it down and waited about 5 minutes. Fired back up and started off, made it less than 2 miles and the light is back on. Pulled over and waited about 15 minutes. Started off and again the light comes on after a short distance. I repeated this 6 times over 10 miles and 2900ft rise in altitude, each time the distance I could ride (on the shoulder and less than 35mph) grew shorter. At one point I started loosing what little power I had, the bike just started stumbling as the power dropped (I assume vapor lock). After I got over the summit I babied it back home with no other noticeable problems. I called the shop in Bishop, and he said I should check the coolant level, and make sure there are no air pockets, and add coolant if it's not up to the top of the fill neck. Now when I start the bike the warning light stays on for 3-4 seconds (before less than a second), and tonight riding down the mountain from work (63F) the fan was on when I got home and parked it. That had never happened before. I think I fried the oil (AMSOIL) and plan on switching back to Castrol full synthetic 4T racing at the first opportunity. Another local rides a Ninja 250 and uses the same shop and told me today he never had a problem, over heating or other, on the ride back up. If I fried the oil and ride a week or so before I change it, do you think that's thats bad? Should I change it asap with what ever I can get (motorcycle specific) even though I can't get a filter up here till Tuesday at the earliest? Sorry this is so long and any suggestions and help are appreciated.