I have been pretty regular changing oil, fuel filter, and air filter but haven't drained the transmission nor changed either the spin on filter or the internal filter. Could I have damaged anything? Do I need to do anything special because I haven't changed the filter.

My plan is to drain the transmission and change the spin on this weekend, then change the internal filter at 90K.

Any advice would be appreciated.

-Frank

What year is your truck/tranny. If it is a 6spd Ally and you do not fit the "severe" maintenance schedule, GM and your manual probably call for tranny fluid drained at 50k with a filter replacement. That is spin in only. The 6spd requires a rebuild to replace any other filter other than the spin on.

Unless you have run that 49k under severe conditions or heavy towing, you are probably fine. Check fluid color and smell when you change it. I would say change it a bit more frequently in the future. I change spin in filter at every other oil change and tranny fluid at 25k intervals.

My truck is 2005 GMC Sierra 2500HD LLY.

I do pull a travel trailer with it occassionally, but primarily I use it for local work driving in Florida.

When you drain the transmission fluid, how much do you have to refill?

You will drain out somewhere between 7 to 8 quarts. Measure what you take out and go from there. Also, there is a magnet on the external spin-on Ally filter, clean it and re-use it. Also, it is best to use a oem Allison filter...

I beleive if you tow a lot filter and fluid at 25,000 and 50,000 if not towing much

spin on filter the info is in the maintaince manual.

Spin on should be changed every 10K max IMO. Sump filter should be changed at 50K max. This is my personal opinion only. It's your truck so do what you want.

maint. is cheap......

maint. is cheap......

Here here.

I just changed mine last week at 110,000 miles. I wouldnt recommend this but I never had any problems.

I was surprised at how clean the oil was and it also didnt have any metal flakes. After I changed it, the tranny noticeably shifted quicker at WOT.

Glad I'm not the only one getting around to changing mine for the first time at 46k. Shhh, don't tell the dealer. Trailering? What trailer? So what if I have a g/n hitch in my bed and I've worn out 2 trailer recivers and the plugin holding plastic is busted from plugging in and out so much...

8-9 quarts @ $8 a quart is painful. Maintance ain't cheap compared to an eco-box with a manual tranny...