Guys, as
nismosleeper was able to discern, I carefully said 'mostly' over-rated because the product
does work, However, there's always a chance with a solvent-based cleaner like Seafoam that it can cause wear if used in too high a concentration or left in a sump for too long.
There's also a chance too much old sludge can be dislodged at once clogging filters and tight passages and doing damage that way.
As that BITOG thread pointed out, Seafoam is over-priced for what's in it (ingredients).
If you want to clean sludge out of your motor, Auto-RX (an ester-based cleaner) is probably the champ. The esters won't harm the innards of your motor like a solvent sometimes can.
Another approach to take is to do a couple short-duration oil changes using a gas/diesel 15W-40 motor oil. Even Supertech (Walmart) 15W-40 is worth using for 1,000 miles or so. These gas/diesel (HDMO) oils contain strong, strong detergent pacikages that will (safely) clean up neglected motors. Not sure how long it will take, however.
If you change your oil using one of these and the oil turns black quickly, it's doing its job ...
... safely.
