What oil did you use before and how much mileage on this engine/oil? What type displacement/engine?
Just be glad sludge is in the filter. Reduce OCI and change filters more often until engine is clean, ir use something Like LC or Auto-RX.
I changed the oil in my Mercury Villager (92,000 mi) last night at 4500 miles on the Rotella Syn. I was very suprised to find a very thin coating of sludge in the bottom of the oil filter. The sludge was in the inner (clean) chamber of the oil filter on the flat surface where the bypass valve would be if it were a bypass type filter. I would think that by running HDDO in this engine that ALL of the loose soot/sludge would be in suspention, am I wrong? Or, is the oil still cleaning out sludge from running non-HDD oil? (been running HDDO for 12,000 miles)