The Joe Gibbs Driven Break In oil (running in) is fortified with more than double the amount of Phosophorous and Zinc normally found in modern engine oils. The first minutes of running in an engine is vital and can be very costly if the wrong oil is chosen. Recommended for all types of engines and used by Joe Gibbs Performance in all their engine dyno work (including power runs). An excellent choice for the concerned and quality minded engine builder