Two oil filters????????................

[Duramaster]

Ok, will someone please explain this to me. I worked on a 2001 GMC DMAX today that had two oil filters (no biggie). One filter on the cooler where it should be and the other was remotely mounted just inches away. It was connected to the cooler with some hose and then the outlet of the filter ran up to the oil fill cap!!!??!!??!! What is the purpose of this???? Both oil filters were AMSOIL filters. I wasn't aware of an oil starvation problem with the injection pump gear. I did not notice anything weird with the oil pressure gauge either. :confused: :confused:

[Mark Rinker]

Like this? http://www.amsoil.com/StoreFront/bf.aspx

[Heartbeat Hauler]

Oil bypass filtration?


JP

[killerbee]

the second element is a non-conventional fine filtration element. It recieves parasitic bypass feed from a pressurized source, like the oil filter housing, but it has very low flow. usually less that 5% of the total oil flow rate. That is why it is parasitic, it tends to reduce system flow rate by a tiny amount.

It's only purpose is part flow fine filtration, down to 2-5 micron. The regular element is good only down to 20-40 micron.

Some time back, I studied oil lubrication needs. The conclusion I came to was that if oil was allowed to heat up past spec (over 220 F), then bypass filtration has more value. I have had oil up to 350 degrees FWIW.

It is expecially valuable for extended oil changes.

[NutNbutGMC]

the second element is a non-conventional fine filtration element. It recieves parasitic bypass feed from a pressurized source, like the oil filter housing, but it has very low flow. usually less that 5% of the total oil flow rate. That is why it is parasitic, it tends to reduce system flow rate by a tiny amount.

It's only purpose is part flow fine filtration, down to 2-5 micron. The regular element is good only down to 20-40 micron.

Some time back, I studied oil lubrication needs. The conclusion I came to was that if oil was allowed to heat up past spec (over 220 F), then bypass filtration has more value. I have had oil up to 350 degrees FWIW.

It is expecially valuable for extended oil changes.Thanks KBee. Most excellent Cliff notes.

:tiphat:

[SoTxPollock]

Duramaster, I have one of those on my truck. I've checked the flow through the bypass filter and it takes a little over 20 minutes to flow all 10 quarts through the 2 micron filter, benefit being that every 20 minutes my oil has been cleaned cleaner than what the original filter can ever clean. It has a .090" hole drilled thru the block off plate where the element is mounted so that no visible pressure drop will occur in the rest of the system. It really works. Costs a little more to change two filters and an extra quart of oil, but thats cheap insurance to allow it to run a lot longer without as much wear from the larger particle sizes floating around in the oil. I don't think there is an OEM filter that traps below 20 microns in particle size so it makes sense to me to filter it finer and hope I can make those million miles I plan to drive it.

[Duramaster]

Well, hopefully the customer brings his truck back soon. He lives in Bend, Oregon and I am located in Portland, Oregon. He travels alot and is here every week. I will try to get some pictures of it. Honestly it looks kind of hokey if you ask me, But the theory sounds good. :)

[jbplock]

... the theory sounds good. :)

FYI .. Over at BobIsTheOilGuy (http://theoildrop.server101.com/forums/ubbthreads.php?Cat=0&C=7) they have a specific forum dedicated to Bypass Filters (http://theoildrop.server101.com/forums/postlist.php?Cat=0&Board=UBB36)

Some of us even have Coolant Filters (http://www.thedieselpageforums.com/tdpforum/showthread.php?t=26656&) in a bypass configuration across the heater core inlet/outlet hoses.

:)

[Duramaster]

I have seen the coolant filters. They are more common in the larger over the road trucks. But I can say that I haven't seen the bypass filter in operation before (in a P/U truck application), but again I can say that I haven't seen it all either. That is the great thing about this website, there is always something new to learn and there is always somebody here that maybe I can help in some little way. :)

[JohnC]

Actually, I'm willing to bet that bypass filters have been around a lot longer than full flow filters! The advent of the full flow, disposable filter put a big dent in the market, though.

[killerbee]

If I may, the stock element is almost never full flow. The closest it comes to full flow is at idle, on a warm motor.

A 40 degree cold motor at 2000 rpm, places the element under an 80% bypass. 12gpm flow is reduced to 2-3 gpm in the element.

This is the biggest reason I suggest using the TD-EOC with mocal thermostat protection: it allows the shortest warmup time for oil, and that amounts to quicker filtration.

I am not a big believer in bypass filtration unless you run hard and hot, and use extended drain intervals. The stock element will filter quite a bit below 20 micron as it loads up. I have toyed with the idea of dual full flow elements, changing only one at a time. That leaves the other "dirty" element to continue finer filtration while the other has plenty of capacity and low resistance.