I change out the oil and filter every 3-5000 miles, but am not sure what to do about the transmission... ive got an 06 duramax 4wd, 90K on it... what needs to be done? Ive never had anything serviced on it. Dont wanna fry the allison!

Moved to Maintenance & Fluids :)

This is a joke, right? You're messing with us? Check your owner's manual. It's all right there...

I would recommend dropping the pan and changing the internal as well as the external spin on filter with a wix filter. Flushing it would not be a bad idea either, then use a nice Amsoil product like Torque Drive in there.

seriously, if you've never had anything serviced, you're way overdue for a few things. do you tow? most importantly is probably the transmission fluid and spin-on filter. 'normal' service says change every 50K miles. 'severe' service (basically, if you tow) is every 25K. while the internal trans filter isn't normally replaced (per the official maintenance schedule), if you've really never replaced the fluid or the spin-on, i would most definately do it. the trans spin-on is part #29539579. not sure what the internal filter p/n is.

as far as what fluid to use, i believe '06's are the cutoff year for Dexron III / VI. if you search this forum you'll find how to determine whether you can use Dex VI or not. you can use a TES-295 fluid instead if you choose. for the list of ACTUAL TES-295 fluids, you can find them here - http://www.allisontransmission.com/service/autoapp/172/viewpage.jsp?ThisPage=3. since you are still inside your powertrain warranty, i wouldn't use a non-certified fluid (like torque drive), but that is your call. since you can get actual certified TES-295 fluids more readily and more cheaply than torque drive, i can't see why anyone would buy it, but some folks do.

whats important is that you get the 90K fluid out of there, and some fresh stuff in. even basic Dex III would be an improvement. IMO, i'd search for the 'hoot' method described on this site and really get rid of all that old stuff. just dumping the pan only gets about 1/2 the total fluid.

as an aside, if you change your own oil, you really should pick up a few of the allison spin-ons and add that to your oil change routine. as a guess, i'd say most folks here change them every other or third oil change or thereabouts. its easy as hell to do and fairly cheap. while every other oil change is probably over-maintaining, given the lack of service on yours, i would definately start on that routine. MAKE SURE YOU TRANSFER THE MAGNET from old filter to new. might want to take and post pictures of the magnet before you clean it off too. i wonder what an unserviced magnet looks like after 90K!

ahm

if you have not kept up with the service then you should check into changing your brake fluid and power steering fluid transfer case and front and rear diff fluids. also flushing the allison 1000 trans is a no no. i have a friend that never changes fluids in his trucks and i mean never. that guy also never seems to have any problems. go figure.

agree with knuckledrager re: brake fluid, transfer case, and F+R diff. Power steering would be low on my list personally, but certainly couldn't hurt. Is there an interval for changing that per GM?

a 'power flush' of the trans - where they hook up a machine and 'push' fluid through it is a no-no as i understand it. the 'hoot' method relies on normal trans pump operation to push out the old fluid - there is no risk associated with doing it this way. if you are really concerned, draining the pan, refilling to the appropriate 'hot' level, and then doing it again will achieve what GM considers a complete fluid exchange. i base that on the fact that two drain/fills meet Allison's requirements for going to extended drain intervals when done with TES-295 fluids. either way, up to you, but i would pick one and do it ASAP. 90K miles is WAY too long for trans fluid in this application, especially Dex III-based.

ahm