I just did the fluid & filter change on my 3.7L Commander, its a NAG1/W5A580 trans. Its a Mercedes trans, there is a Mercedes designation as well, 722.3 or 722.6, NOT sure on that number. I installed a trans temp gauge and installed the temp sender in the pan, which of course means dropping the pan and changing fluid, so you might as well change the filter with it.
This trans has a pan gasket, and its a really neat design that works really well. It looks like it is re-usable to me, BUT, considering the pain it is to change the pan gasket, its worth it to buy a new one to avoid the chance of having to do it again.
From what I understand, this trans is super sensitive to being overfilled, so you have to be ultra-precise. That is probably the reason its a dealer only service. What I did to make sure I didn't overfill, I measured how much fluid I drained and replaced it, as well as check it with the dipstick tool.
You check fluid level with a special tool, that is just a dip-stick with a really nice scale on it, and the temperature of the fluid and adjust fluid level off a chart. The procedure is too use the dealer tool to read the trans computer reading the temp, which is probably the most convenient for the dealer mechanic. I don't see why reading the temp with another tool would make it any difference, as long as its accurate.
You will need:
*The dipstick tool, I got mine off ebay for $25, special tool, CHY933 10.
*A torque wrench capable of 70in-lbs or 6ft-lbs.
*T-30 Torx Tool that fits your Torque Wrench
*Something to measure the trans fluid temp, I think a good thermometer pressed up against the pan would suffice.
*Temp vs Fluid Level Chart in the FSM, available on the internet.
I got a federated filter, it came with the pan gasket.
The bolt heads for the pan are Torx, T-30, they are torqued to 70in-lbs, and that is tight enough that I had to strain a lot to loosen them with a Screw-Driver like Torx driver, and I'm a big guy, so get yourself a T-30 torx for a socket wrench. You'll need it for your torque wrench to torque them down properly later, anyway.
The FSM says to change the oil when its hot, to idle the motor until its at full operating temp.
Have an old towel, you will spill fluid, there is no way around it unless you find a 3 ft wide catch pan. One of the 6 retaining lugs also attaches to a cover of the electronics, remove that bolt before dropping the pan or you'll bend up the cover slightly.
The filter just pulls out, lube the o-ring on the new filter with some trans oil before pushing it in.
Clean the pan and the magnet in the pan, clean the old or replace with the new gasket, bolt back up the pan and torque the bolts to 70 in-lbs.
The FSM will say the pan holds 7.4 qts and to fill with 7.4 qts after dropping the pan. IT'S WRONG: and thank god I didn't listen to it and measured the amount of oil I drained before filling it, I only drained 4 qts of oil. I would have overfilled the trans by 3.4 qts if I didn't check, that would have been a major pain to drain and would have caused trans problems if I tried to drive with it that overfilled.
When I checked fluid level before starting the engine, the fluid level read 40mm over what it was before and easily 60-70mm more than it should have been at that temperature. But, since I had measured how much I drained and replaced it with the same amount, I decided it must be displaced fluid and would all settle down after circulating the fluid some. I took the vehicle for a slow drive, got the fluid temp up to 150°F and checked again on a level surface, and the fluid level was exactly where it should be.
The FSM says the trans hold 8.55 qts total, so when it said dropping the pan would drain 7.4 qts, I was psyched and figured I would change enough oil with a pan drop that a flush would NOT be required. But its NOT true, like most trans, dropping the pan only drains a little less than half the fluid. Other vehicles I have disconnected the return line and idled the motor and poured in new oil as the old oil pumped out. BUT, looking at the cooler lines and fittings I don't know how wise it is to disconnect those lines and try to rig them up to a bucket.
So right now, I have approximately 50/50 new AMSOIL Synthetic ATF and 25k mi. ATF+4.
Last edited by Mongo; 10-30-2010 at 02:53 PM.