When to change trans fluid?

[LEE BROWN]

06 With Allison automatic, I do some towing, (weekends in the summer) has 32,000 miles on truck and fluid. Is it time to service trans fluid? Also what brand/type fluid and filter if it is time? Thanks

[Mark Rinker]

I would say that it is slightly overdue, but your Allison will be fine unless the fluid is already burnt, dark, and stinky. If its still translucent and pink, chances are no harm done - just time for some fresh fluid!

As for fluids:

http://www.thedieselpageforums.com/tdpforum/showthread.php?t=18579&highlight=allison+fluid&page=2

And since you have a 2006...this is a good read as well:

http://www.sandyblogs.com/techlink/2009/05/dexron-vi.html


As for methods:

With this many miles already on, I'd flush the whole transmission and replace with new, then start a regular 7qt "drain and refill" method (partial change) every other oil change interval or 15K miles, whichever comes first, replacing the spin-on external filter each time. Make sure the magnet gets transferred from filter to filter. There is no need to change the internal filter.

What is the status of your front/rear diffs? Transfer case? If any are still factory fluid - its time. Search the forms for all the information you'll need. I am a big fan of synthetics in diffs...mostly due to low volume and high temps that can be encountered, like summertime towing 2WD for the rear diff, and wintertime slippage/stuck in a snowdrift scenarios for 4HI. When the paint bakes off your differential, there is some serious heat being generated into that fluid.

[spongebob]

my dif cover has paint chipping off...*gulp*..
i changed the fluid like around 300 miles...what do i need to do??
i went to a synthetic too...

[Mark Rinker]

Most of the diffs do this - my thought is that synthetic is the only way to go, if there is that much heat being generated into a low volume of fluid with no 'radiator' to dissipate the heat...

If you tow heavy, more frequent diff change intervals are probably in order. We do 50K...or annually in the fall before snowplow season.