I uased to be a believer in high-oil percentages and generous amounts of castor but I'm changing my mind these days.

You sould try a *good* synth oil with just a trace of castor at much lower percentages (assuming a BB engine), you'll be surprised at how much better your engines will run, how much extra power they'll put out, and how they still last virtually forever.

Not only that, you'll save a snot-load of money on your fuel costs.

I used to mix 18%-20% oil (including castor) into my fuel and it cost a small fortune. CoolPower Pink (castor/synth blend) is around $65/us-gal here in Kiwiland. That 3.8 litres of oil only makes 19-20 litres of fuel and I can burn that in less than a month (I fly a lot :-).

Since switching to a "better" oil and using less of it, I'm able to mix over 30 litres of fuel from a single 3.8 litre jug of oil. What's more, because there's more methanol in each unit of fuel, I get the effect of running about 12% nitro, even though I only run 5%. Some of the guys run 0% nitro and their engines perform better than when they ran CoolPower oils (20%) with 5% nitro.

In a land like Oz and NZ where nitro is mondo-expensive, being able to mix *cheaper* fuel that produces more power with no discernable bad effects makes a hell of a lot of sense.

Yes, keep your 20-25% castor for those old lapped iron-piston and/or bushed engines, but today's modern ball-raced ABC/ABN and ringed engines just thrive on a lower percentage of better oil.