Was talking with my Mitsu connect today and oil filter subject came up... Did anyone know that there is a check valve in Mitsubishi's filters? There is... reason for this is so that oil in you motor does not return to sump on pressure side. The result is that you are starting the car with oil already at the lube points rather than with aftermarket filters the pump must build up the pressure and fill the passages. This means when we are first starting the motor, especially after a long rest, it is starting with vertually no lube for a split second. For us turbo owners this also means the same for the turbo. They have a display showing this and he went on to explain about the Valve lash adjuster noise. Seems my noise goes away when the car is nice and warm... not all the way but for the most part. It's noisy as hell when i first start it though. He said this is why Mitsu designed this feature. It keeps oil in the Valve lash adjusters when the car is off. Other filters allow oil to drain back and when you start the car air gets into them. Thus you get noise till you've driven a bit. Interesting theory and enough for me to buy a couple to test this out. They are offering 3 filters for 14.95 right now. A little expensive but nothing much. I'll let you all know what i find out as this is one interesting concept/detail worth studying!

 

Well keep in mind that just about every oil filter out there from Bosch, Wix, Mobil, and even my (non)favorite brand Fram have some form of an antidrainback valve in the oil filter. Some of them don't, but they're pretty rare items. It's not even really a valve, it's just a donut of nitrile rubber or silicone that gets pushed back against the holes to prevent the oil from draining out as Boe said.

Here's some guts of a Bosch as an example...



Yes it's a very important thing for turbo and even non turbo...anything that keeps oil up in the head/cam/lifter for startup is good. Unfortunately, even with the anti drainback, it ain't perfect, especially in cold temps where the rubber material gets stiffer and doesn't compress as easily to seal.

 

I use fram and when i checked there was no such thing inside it. Maybe it is only a certain style that has it. All the other ones that i have used like, puralator/penzoil/etc... cheapies ya know, have not had them either. The bosch one is a different design from the mitsu one i saw. The mitsu actually had a spring system in it. It was a weak looking one but it was there to assist in the seal when the pump was off. Have you checked into the mitsu filters? I'm going to buy three and see for myself. Also i believe Wix is about the same price as mitsu's. Don't know about the others. I'm going to investigate a bit tommorrow and well post it. Hell $5 bucks is nothing in my book for a oil filter. The difference of a hurt motor vice a well oiled one is worth the extra $3 for mitsu filter. Thanks for the info diesel. I'm going to get pics of Mitsu filter tommorrow if i can. I'll post!

 

I bought one Mitsu OEM filter before realizing that they didn't give me the MD356000 which came on the engine, but the MD325714 which was a bit thinner in diameter. The antidrainback looked like hell as it wasn't rubber, but plastic - I haven't cut it open yet, but I intend to this weekend. Are you sure the physical spring was the antidrainback? There is sometimes a spring coil in the filter to keep the element securely in place against the baseplate. When I get a MD356000 or see pics of it dissected, I'll decide if it merits anything special.

Every filter I've cut into so far have a bottom mounted bypass valve arrangement like pictured on the Bosch which casuses oil to wash the element before actually making its way to the engine. Also if there is any dirt or sediment at the bottom of the filter, it's in a prime spot to be pushed out of the filter and into the engine. I'm using a Napa Gold made by Wix, with a top mounted bypass for this reason.

I look forward to your pics.

 

http://knfilters.com/oilfilter.htm

The filters I'm putting in next change. Since it says (where applicable) I'm guessing I should cut one open for posterity?

 

Hobie, FWIW, don't cut open a perfectly good K&N unless you really want to look at its guts. It should have metal endcaps, the antidrainback at the top like the Bosch I posted and hopefully the plunger style bypass also pictured. The K&N is made by Champion labs, the same company that makes all the following filters: Mobil1, Bosch (Premium and Normal), STP, and SuperTech at Wally World.

The K&N is supposed to have amongst the highest flow rate since it's got the least restrictive media amongst the brand names mentioned.

I just hacked open an MD325714 and I'm going to post pics. The idea presented that Mitsu oil filters are special since they're the only ones which have antidrainback valves is not correct as the one I just cut open has exactly the same style of antidrainback as the Bosch.

 

Now that is what i wanted to know. The one that is cut open at mitsu does have a spring but after talking to the guy he said that has been there for a decade. Thus they have probably change things like all the others. Lets see the pic... go diesel fan go!

 

Okay, as promised here are the guts of an MD325714

















After looking at this thing, I wouldn't put it on my Lancer or anyone else's for that matter. It has cardboard endcaps like a Fram, filter media that looks like it was burnt in the oven when it was cured, and a cheezy type bypass spring that looks as if it could be easily stuck in the open position. Moreover a bigger concern is that there are not pleats all around the external surface of the filter. Combine this with the very restrictive input path and I can see why Mitsubishi makes such a big deal about their oil filters being able to withstand a 250psi burst test. With cold oil, especially dino which tends to coagulate, there would be one hell of a pressure spike as it tried to flow in through the tiny slits in the top endcap. There is virtually NO extra clearance around the can from the element surface, thus a lot of resistance to flow.

My subjective conclusions. I would never use an MD325714 for the reasons pictured above. I think that once the outside 'flat' areas of the filter media became plugged with dirt or contaminants that the filter would become increasingly restrictive to flow, meaning that the bypass valve would be open more often to provide proper flow. The whole cold / winter start issue I've already mentioned above. If I had no other choice, this filter wouldn't be on my engine for more than 3k, no matter what oil type used.

If the MD356000 is constructed the same way, I wouldn't put it on an Evo or anything else I value mechanically. This is a big IF since I haven't seen the guts of the MD356000 yet, as my local dealer sub'd the above part # when I asked for a Lancer oil filter.

Something to keep in mind here is that many times the Japanese OEM filters when installed at the factory are a cut above in terms of quality compared to what companies such as DensoUSA are contracted for to produce as the OEM part on our shores. If you peruse the Honda / Acura boards out there, you'll see this discussion more than several times. My 4Runner v6's original filter installed at the factory in Japan was equivalent to the TRD Toyota part ordered from my local dealership, at a nice price premium of course!

No more dremel action for today....

 

Now that was an indepth and complete post. After checking one out today it wasn't the same as their display. It was exactly as you show above. I bought 3 so i'm stuck with 2 more oil changes then it's back to aftermarket. I was really dissapointed to see such an inconsistancy in mitsu's product vice it's display. Oh well... thanks diesel for the work on this... everyone is now more wiser on this subject... question is which filter to use for the dollar?? imp: ---->desiel fan!

 

Thanks for the Boe. If you're concerned about maximum flow / least resistance, I think Hobie is on the right path with the K&N. The filter can is not quite as thick as Mobil1, but it's very strong. K&N touts flow rate and some tests I've seen run on another forum seem to confirm it. The Mobil1 also made from Champion Labs has a larger flow drop / more restriction since the synthetic media is designed to filter down to 10microns which is pretty small.

Another supposedly very good filter is the Amsoil, which is actually made by the Baldwin filter company. I bought (2) Baldwins from a diesel supply place, they have a very interesting looking center tube. Instead of circular holes, it's a spiral louvered pattern along the entire length with no gaps.

I still like and use the NAPA Gold made by Dana/Wix. It supposedly has a hybrid / spun glass media for both good flow (still less than K&N though) and a good filtration rating. If I'm bored tomorrow (which I likely will be), I may dremel away at a few filters I've got. I also still need to find a dealer around by me that actually has the MD356000 in stock or I'll just order it over the net I guess.

 

I'm soooooo glad I didn't waist my $ on those junk filters!

 

Ok, now I'm obligated to kill one of my purdy K&N's.

EDIT: So naturally that means that I can't find my camera. I'll post pics once I find it.

EDIT EDIT: Found it. Battery's dead. Dremel's in the garage. Pics tomorrow.

 

Here goes. Too lazy to diagram, but you can see how differently designed the K&N is. The combination of it and the Mobil 1 actually smoothed out my idle a bit, allowed quicker warmup and also seems to have helped with my decel stalling problem at bit as well. Go figgur. Seems part of my problem was mechanical after all (though only partially because the realy problem still clearly lies in the EMS).

BTW, too lazy to diagram right now and you can see the parts on the K&N site so here's just my analysis. The construction's actually really cool. BTW, part number is HP-1010 for anyone interested.

Before the ****storm that is my Dremel:

 

Here's a pic of the leaf spring used to keep the element in place so that oil can flow freely around (and then through) it.

 

A pic of the filter element with the leaf set on top. The leaf is free floating once you open the can so it's really just placed there, not attached to anything.