The Rumble strip comment reminded me of when I had torque converter clutch chatter caused by improper fluid in my Transmission courtesy of a nationwide transmission chain that should have known better.
YOu likely have the A 518 which is sturdier than my A-500, but both of these transmissions despise the bulk Universal fluids that transmission shops use. They will say that all they have to do is add such and such a product,a friction modifier, and it will magically take their low grade ATF and turn it into a Synthetic ATF+4.
Effing bullshit.
Mine would do the rumble strip thing at 47 to ~65 mph under light acceleration. HArder acceleration and it would downshift and not occur. I wound up driving a great distance just trying to minimize the occurrence ia the gas pedal.
Solution was having the lines flushed at a Dodge dealer with then ATF+3/7176 fluid, as ATF+4 had not come out yet.
Now it is nothing but ATF+4. NOt a rumble strip since I got the correct spec fluid in there, and that was 70K miles ago.
I put a drain plug in my ATF pan so draining and replacing 4 quarts of ATF+4 is simple and not messy.
I've an additional transmission cooler in front of my radiator, plumbed before the radiator ATF cooler, and on the flex lines i have a Magnefine filter.
The filter in the pan only filters particles as low as 100 microns, where at the magnefine will filter particles down to 20 microns, and has a magnet to catch ferrous material, and a Bypass for if it gets too restrictive.
I will be adding a remote oil filter just for the ATF and getting rid of the magnefine inline filter as they tend to weep ATF, in my experience.
These Auto transissions seem to have an average lifespan of 130K miles with average maintenance performed. The high top adds a lot more stress to the overdrive unit at highways speeds and they say it is the OD which begins to fail first and take out the rest of the transmission.
All one can really do is prevent the premature breakdown of the correct ATF fluid by not letting it get too hot. Extra filtration can't hurt.
I also keep mine out of overdrive at lower speeds when climbing hills or needing to accelerate. Mine will go into overdrive at 28mph under light loads, but the lock up torque converter will not engage below 47mph
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