Buffalo, I'm finding (after searching other forums) that there are a lot of satisfied ATF DW-1 users. No automatic transmissions (A/T's, my shorthand) quitting because of it, at least through my searching. I get more confident in it every time I look. All of the descriptions point to it being a solid ATF choice so far. I can't remember where I found it, but I actually saw a guy with a small pickup truck happily using DW-1, and I don't think it was a Honda Ridgeline!
Viscosity numbers are a weird beast, because sometimes they do not describe how well a 'thin fluid' can act like a more viscous one turning corners in a control valve body or other area where one might desire more viscosity, but then it acts like a thin fluid when running through linear passages or inside a pump, thus reducing pumping losses and delivering the side benefits of better fuel economy and less heat generation. In short, it's not out of the realm of possibility that chemists & engineers can make an ATF act like a multigrade oil...not a great analogy, but it's the best I can think of. I knew this from a previous life in the lab, but it took 02Ody02 to remind me of that basic truth.
The internal ATF pump in our A/T's moves fluid to primarily three different major circuits as far as I can tell from the Helm schematic:
1.) The torque converter & its clutch control valving
2.) ATF cooling circuit (lines leading out of the A/T to the coolers and back to the sump)
3.) Fluid power circuits in the transmission casing.
The TC/TCC control valve & the cooling circuit are almost linked together because they "share pressure" in a balanced sense I don't quite understand. I came to this understanding by reading funtown89's informative posts. Anyways, for this discussion on filters we can treat the ATF cooler lines like a separate circuit coming out of the tranny's ATF pump. It moves a lot of fluid. So, on to filters.
The ATF strainer inside the sump of your A/T is a fairly coarse filter element that cannot be serviced by the user; it requires splitting the case to get to it. All of the fluid returning from the above three fluid circuits will return to the sump to pass through this sump strainer which is just prior to the A/T's internal ATF pump inlet. The majority of small particulates are supposed to pass right through this sump strainer to be held in suspension in the ATF until a drain/refill.
The OEM cartridge ATF filter (black cylinder-shape) on top of your A/T takes care of some of the fluid running through the fluid power circuits in the tranny case. I don't know if it is upstream of those solenoid screens that are the topic of the "Root Cause and Fix" thread. Anyways, after passing through these circuits, the fluid falls right back into the A/T's sump to go back through the A/T sump strainer and internal ATF pump again. It catches smaller stuff that passes through the sump strainer.
A Magnefine installed after the radiator in-tank cooler (those 3/8" hose nibs sticking out of the bottom of the radiator), and before your added additional ATF cooler will catch particulates moving through this separate cooling circuit from the ATF pump. By this time, fluid has passed through the rather coarse A/T sump strainer, the A/T's internal ATF pump, and to the cooling circuit which has your installed Magnefine, which should then also catch the smaller stuff. Those solenoid screens mentioned above are not part of this circuit.
Buffalo, best I can relate since it was explained to me by someone with real knowledge of the subject, is that a 78-deg C (172-deg F) tstat will begin to open only a few degrees earlier than the 82-deg C (180-deg) tstat. As far as I can tell, that rated temperature is when the tstat begins to open. Say, one engine has a 78C tstat, the other has an 82C tstat...the Ody with the 78C stat will start moving hot coolant to the radiator before the Ody with the 82C stat does. If both Ody drivers are using the same amount of fuel, they have near-identical heat exchange needs at the radiator after both of their respective tstats are fully open. Once both tstats are fully open, the coolant temp difference at the cooler bottom tank (outflow end) of the radiators ends up being far less than the difference in tstat opening temps, or none at all. This radiator bottom tank is where your radiator in-tank ATF cooler lives.
I am curious, where did you get the 113F measurement?
OF
