Try and clarify myself the cylinders are in same line when laid over oil will accumulate on the lower walls of both cylinders as drain back is slow when i tried it on the side i didnt have the sump vented to atmosphere i suspect pressure build up in sump helped oil get past rings when i went vertical i vented the sump at the same time so may be if u vent the sump withit laid overand see what the results are as i have not tried that Pete

