[Cougar429]

I would be less concerned with colour than nitro content and lube percentage.

Helis normally run more nitro to increase the power/weight, but I have lived by the rule for planes that if you require higher than 15% to have enough power to fly you have mismatched the engine and airframe.

As for lube, unless specialty such as YS, 4-strokes normally require less due to their lower top end RPM. For years I have successfully run a fuel that contains 18% lube in both 2 and 4-strokes throughout the fleet. At first it was a mix of synthetic and castor, although the maker switched to all synth recently.

The difference is castor can tolerate higher temps and is insurance against lean run or inadequate cooling air conditions. It's messier and more work to clean.

If you have a tach, match the prop so your OS and Saitos peak at the mid to high 9K range on the ground. Do not go above that.

ps. I have a pair of the Saito 125's and they are very strong performers. You will notice some serious consumption until broken in so consider that when estimating flying duration. The second burned close to twice that of my first with more time on it and has since settled in.