After parking the truck (2000 4wd blazer) on an inclined driveway over the holidays, I noticed I am leaking transmission fluid from the front of the pan. I went to get a new gasket and filter from AutoZone and there are two different part numbers one for a deep pan and one for a shallow pan. How do I know which one I have, do I need to change the filter?(145k miles) And is AutoZone system correct that I need 11.5 qts of fluid? (I'm going with Castro dex/merchandise high mileage so 11qt is $$$$)

 

Yes, change the filter. Yes, automatic transmission take a couple gallons or so of fluid. I don't know how touchy automatic transmissions are....but I know the New Venture manual trans requires a specific fluid which I could only get from the dealer. I would search a little on the forum for your type of trans and see what others say about the fluid.

If you have a second vehicle (or a ride) you can be sure of your gasket type once remove the pan. Or you can look at the ID number on the transmission, or RPO code or the VIN (if tranny is original to the truck)and call your local dealership and they should be able to tell you.

Take this for what it's worth....but if you remove the pan and there is no gasket...don't put a gasket on it. Clean the mounting surfaces real well (don't scratch them) and then use Ultra-Black RTV sealant. I just learned this recently, but apparently there are some transmissions (like in my Durango) where you are not supposed to use a gasket because those cork gaskets they will sell you will leak. Once again...take that piece for what it's worth...but I found out that the info was accurate on my Durango.

 

By the way that should be dex/merc high mileage.... Autocorrect....

 

Shallow pan is flat on bottom Deep pan has two levels on the bottom about an extra inch

 

They take the same gasket, its the filter that's different (length of the tube dropping it in the pan)

 

I am going to have to disagree with what you said here.

 

The whole post or a specific portion(s)?

 

Ac delco sells a kit with a gasket and filter together. I bought mine from Rock auto. Like Neo said the only difference in the pans is the depth and they are interchangable depending on the filter used. Some people swap the shallow pan for a deep one if they do a lot of towing or anything that causes excessive heat in the trans. Stick with the one you have I was just using that to prove a point. Like Lewhite said "Shallow pan is flat on bottom Deep pan has two levels on the bottom about an extra inch" so just look under there and figure out which one you have so you order the correct filter. Also if you are only dropping the pan and changing the filter you won't need so much fluid. You will probably need around 5-7 quarts max. Just dropping the pan won't completly drain all the fluid like an oil change does so the best way to tell how much to add is to make sure you catch all that comes out and then find a way to measure that (use and oil oil bottle or something to get close) and add that much new. I bought Valvoline Dex/merc for mine after reading dozens of threads and that seeming to be the most popular and recomended fluid to use. Lastly don't ever put silicone of any kind on your blazers trans pan please! I know there are some out there like rockp2 said that require it but it will only give you more leaks on the blazer. Just make sure you take your time and get any old gasket cleaned up really well and ensure that both surfaces are clean and debris free and then put the trans pan back on carefully. Be careful not to overtighten the bolts the spec on them is 124 inch lbs. Hope this helps a little!

 

Not using a gasket was hard for me to believe also. But there was no gasket when I dropped the pan on my Durango (pan had never been dropped). If I remember correctly (it was about a year ago) I went to dealer to buy a gasket because autozone wasn't to sure which one fit my trannny. They told me there was no gasket and about using sealant only. I was still skeptical, but followed there direction...haven't had any leaks. But as rexmburns stated, it apparently only applies to some transmissions.

 

That was the part I was disagreeing with, that method would not work on these trannys. Some, it may.
But I honestly would never do this on anything.
But, i'm weird. LOL