I added 1.5 ounces/gallon of Lucas Upper Cylinder Lube. 20 HP Briggs V-Twin Definately quieter tappets. I was getting an oil temperature of 200*F at the bottom of the sump...today the temp was 180*F at the bottom of the sump. Too soon to make a statement....but hopefully encouraged. Seems like the product performs. Spark plugs look fine.