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The 30% Cool Power Heli fuel I will be running in .049s.  It has 30% synthetic lubricant.

The 10% Omega sport fuel I will be running 15s to 40s.  It has 17% total lubricant, 30% castor and 70% synthetic.

I want to make a quart of each for control line use by adding castor oil.

How much should I add?      

Cool Power Heli fuel is 30% nitro and 24 % synthetic oil, no castor. Omega is 17% of which 2% is castor. Neither of which is readily adaptable to 1/2A running. The heli fuel has plenty of nitro but at 24% oil you can't really go bumping up the castor to any large number. Using 10% nitro in a 1/2A is like running it in 2nd gear. Small engines thrive on nitro and reun best on a minimum of 20%. the old Cox formulas that Cox sold were 25% sport and 30% Red can racing fuel. Both of these fuels were about 25% castor oil.
You can doctor the Omega and make it useable for your larger 40 sized plain bearing engines.

Dennis