[Dino_D]

Lower grade oils could get hot enough to boil. Although I haven't experienced that yet.
The biggest reason for the change to the higher grade oil, is when the brakes are heavily used, the caliper heats up and starts to push against the pad (as I mentioned earlier) and it causes drag on the brakes, eventually expanding enough to lock the disc completely and ruin your race until it cools down. Dot 5 isn't effected by it.

H2Toy: What pipe are you using? 2-stroke engines have the biggest performance gain from changing a pipe.

Also what 2-stroke oil are you using? I recommend Motul 8002T 2-stroke oil. There are 2 versions (on road and off-road) - It causes less wear on the engine.
They finally made a Motul Micro 2T for R/C vehicles which can be used for Methanol, Nitromethane, Ether fuel. Haven't tried it yet on my nitro cars, but it will be interesting to see how it performs.
Castrol A747 and Castrol TTS are pretty good as well, along with Elf.
Don't use Redline, FG stroke, Yamaha 2 stroke oil. It makes the insides all black.