Ive never used it in an engines crankcase, but I always have a bottle laying around. Washing machine transmissions love it. Its whats in my 25 year old washing machine now. OE washing machine transmission oil looks, smells and feels like Lucas. My pressure washer takes 20 oz of oil, but the OE oil comes in 16 oz containers. I use 4 oz of Lucas to top off. The pressure washer crankcase never foams up like some will say Lucas can do. The pressure washer works well and has for many years and hours doing this. Before, the pressure washer pump oil would be thinner than water after a few hours of use. When the hydrostatic transaxle on my mowers need a change, but I want to finish up the season to change, I'll drain some fluid and add Lucas. Pretty much anything that calls for a ND oil that you want to thicken up a little, Lucas seems to fit the bill. But once again, Ive never used it in an engine.