Originally Posted By: LckydevL
Sure, I could pick it apart and blame a number of things that could have caused the sludge.
Well, in a good engine, your OCIs certainly weren't long. However, as I pointed out, there were other issues with those trucks. As stout as they are, a bad PCV and carb were the weak links and could easily cause major issues.
In my fleet usage, fuel dilution issues were not possible (LPG), and sludge was simply never seen, with 6,000 mile OCIs. There was no short tripping, either, though.
Back in those days, just about every conventional was picked on for "causing sludge," including Quaker State, Pennzoil conventional, and Castrol. Considering the stories I've heard versus my fleet experience and experience with my own vehicles, the two variables that stand out (aside from improper maintenance) are fuel dilution and short tripping.
The feedback carb in my old F-150 would dilute the oil so bad that near the end of a 3,000 mile or less OCI, a 30 weight oil would allow the oil pressure light to flicker on with the oil hot and the engine at idle. With a 40 weight, HDEO, that problem disappeared. Now, after a rebuild and a real carb, hopefully it won't recur.