Pro Honda GN4 All Purpose Engine Oil. Honda set the standard for motorcycle oil with GN4 way back in 1975. GN4 uses the highest-quality base stocks and an additive package designed for the unique requirements of motorcycle and ATV engines. Thanks to constant testing and development, GN4 meets the demands of today's engine technology with higher levels of cleanliness, more stable viscosity and even better shear resistance. Created with the highest quality base stocks and additives in mind specifically for your ride. Continuous testing and development resulting in a lubricant with better shear resistance and viscosity stability. Designed to meet the requirements of stresses in the new era of engine technology.