SD2
First, just so happens that this morning, I was looking at the oil system in the overhaul manual and in my opinion, MD gave a good (and accurate) description of the system.
I agree with your thoughts about inspecting the screen vs the filter element. It?s a lot more time consuming to inspect the filter. But for me, I don?t mind doing it, so far. As an option, you can send the filter (or just the element or just the material from the screen) in with your oil sample and have it looked at, under a microscope, for an additional $25.00 or so.
Let me say right here and now, that the rest of this is my opinion, OK?
On the plus side for the screen, all of the oil has to go through it. That, by it self, gives it a pretty darn good chance of catching all of the part numbers that go through it. MD, am I right about that?
On the down side for the filter, it has a pressure bypass that opens at 8-10 psi of differential pressure between the inlet and the outlet of the filter. My concern here is when the oil is cold and really thick, or obviously if the filter is plugged up, it?s not going to go through the filter medium. It?s just going to be recirculated with out being filtered or screened.
On the down side for the screen, it has no ability to ?clean? the oil as it goes through the engine, lap after lap after lap...it can only ?strain out? the bigger pieces. Obviously, that?s a plus for the filter and was the selling point for me. My hopes are that by catching as much of the little micron size stuff as is possible, the engine is going to last longer (get the grit out of the oil).
As for the bit about extending the oil changes to 50 hrs, I keep hearing that, but haven?t found the documentation yet, maybe someone could point me in that direction.
I do have to say that it sure is a whole lot easier and cleaner to change the filter then it is to remove the screen.
Neither system is perfect, nor are they a substitute for an ?element inspection? and oil analysis at every oil change. But I got to ask, how many wrenchers have torn a motor apart just because an oil analysis came back with a slightly high reading, don?t we all wait til we can read the part numbers in the screen or until it?s knocking?. Maybe it?s happening a lot more then I?m aware of?
Another one that I heard, was that it was cheaper to run a filter then it is to run a screen, here?s my take on that. Lets assume that both engines go to TBO (2000 hrs), both are topping off with 8qts of oil and the filtered engine is changing oil every 50 hrs instead of 25.
Screened engine:
Oil change every 25hrs plus Oil analysis
8 qts oil @ $20.00 plus sample @ $12.95 X 80 changes = $2636.00
Filtered Engine:
Oil change every 50hrs plus oil analysis plus filter
8 ½ qts oil (you got to fill up that filter) @ $21.25 plus sample @ $12.95 plus filter @ $13.90 X 40 changes = $1924.00
But wait!, what did you put that filter on?
(1) B&C Oil Filter Adaptor @ $468.00 + $1924.00 = $2392.00
That?s a savings of $244.00 over the life of an engine or $0.122 cents/hr. or @ 100 hrs/year = $12.20/year. Not enough to buy another oil filter but....Eureka....I finally found the funds to support my beer dependency!
I hope I don?t ever hear again ?how much cheaper it is to run a filter?.
It?s the cleansing effect (or myth) of the filter that sold me.
Sorry about the long post.