Crankcase Cleaner ???
 

Before I change the oil, I want to clean out the old sludge, carbon, etc. in the crankcase. I know they make an additive that you pour in the crankcase, let the car idle for about 5 minutes, then drain.

Has anybody used these products? Which product do you suggest?

In other way to clean out the old deposits without dropping the pan?

The car is a '91 LX 5.0 Convertible.

Thanks
Larry