Actually you never know how much additive to add. If you can get a copy of the chemist report as to API, cetane index, etc., then maybe you would stand a much better chance. The chemist who ran the variable compression engine and compared it to a reagent grade Fischer Tropsch mixture should document on the report how much of what was used to push the fuel to whatever cetane number over 40. You can then run the calculations to see what your additive can push it further. Sometimes you can get the Power Service claim, sometimes not. Sometimes it takes more, sometimes less. It depends.