Absolute best sludge/varnish cleaning CONVENTIONAL oil..

[ChrisD46]

I have run PYB (GTX Ultra Clean would also work) with a bottle of High Milage Rislone for a 3K OCI and saw nice improvement ... The same oil with 1 oz. per oil quart capacity of Sea Foam for the last 250 miles of the OCI also worked . Next , I would run shorter OCI's of any name brand synthetic D1 / Gen 2 rated oil for a couple of 3K mile OCI's and you should be good (of course , changing the oil filter each time) .

 

[Luftmasse]

IIRC, some here are saying it cannot clean up the sludge, but it can help prevent sludge build up. Unless you use some kind of solvent, it will aid in cleaning.