Regarding, the use of B-12 Chemtool Fuel Treatment (part #0116) in the crankcase, it should only be done immediately before an oil change. It is extremely effective in the removal of gum, sludge, and other deposits that can cause such a ticking. However, there is a caveat. If sludge or carbon build-up on worn oil rings has been helping to seal the crankcase, then applying B-12 could actually cause the engine to begin smoking even if it didn’t before. This is an uncommon occurrence, but please be aware of the possibility. If you would like to use B-12 as an engine flush, pour into your cold crankcase approximately 1½-2 oz. of product per quart of oil capacity. For instance, if your Suburban holds 5 quarts of oil, then you would use 7.5-10 oz. of B-12 or about half to two-thirds of one can. After you’ve added it to your cold oil, start the car and run it at idle 10-15 minutes or until the oil is fairly warm. Then change the spent oil and replace the oil filter.