by qaz
"Plus, if the problem is that the stock filter doesn't flow enough, as some claim, then how can the problem be that the oil drain passages from the head back to the pan don't flow enough?
If the problem really is that the oil stays up in the heads too long, then putting a high-flow oil filter on will just make the problem worse (assuming that the oil path is pump-filter-heads)."
Just to comment - I do not think I or anyone else claimed the oil filter WAS the problem. More that it COULD BE a problem, and still could. This information suggests that either the oil pump is rapidly pumping ALOT of oil to the heads to lube those 4 fat hollow overhead cams, or the oil is hanging up in the heads along time (or both). The point of the oil filter discussion was that the Motorcraft and other filters had NOT BEEN TESTED to high flow rates that the pump is capable of. This means that the filter bypass mechanism flow capacity was NOT TESTED EITHER. Maybe it works well enough, maybe it doesnt, but I wanted it tested! K&N is the only one that does (and BTW turns out to filter better than Motorcraft in DEMON SVTs oil analysis comparison).
As far as making the problem worse, this makes no sense to me. If the filter IS a restriction, it would mean the oil would just sit in the sump until backpressure dropped. Oil sitting in the sump does nothing, it HAS to be pumped to the heads where gravity lets it drip down to the bearings where it is needed. This information (if accurate) suggests MORE oil is needed in the system - in the stock pan, in a bigger pan, in Accusump etc. Consistant with what I learned from the racers, it explains why baffling is of limited value. A high flow filter will just help ensure that it is pumped efficiently to the heads so it can drip back to the bearings. This info does argue that the filter they were using (presumably Motorcraft but who knows) presumably does flow well enough but I am not sure the case is closed on that either.
