Originally Posted by 2five22
If you are using quality fluids and lubricants, buying unspecified additives is a waste of money.
X2, the only exception to this is if your are having some lifter noise, then add some Marvel Mystery oil, one (1) pint. Run your engine for about 100 miles and then change it when hot. The additive will help to clean out your engine and has been used successfully for years to help with noisy lifters.
Other than this, additives are not needed!