Checking my logic - fluids

[4thgenceli]

Been a while since I've been this deep in a project. Me & the boys have loved every minute of it though. Wrapped up the motor and started to drop it back in when I noticed a nice wet spot on the front of the transmission (not the input shaft, but whatever the plate just below that has).

Not able to find the seal locally one of the shops suggested just pull the cover off and put a small silicon bead on it (the seal supposedly only comes in the full rebuild kit). In doing that though I'm going to lose most (if not all) the gear oil. Figure may as well do it, drain and replace it (and the t-case and front/rear ends while I'm at it).

The problem I'm having though is what weight goes in each? I hear 75w90 in the transmission, ATF in the t-case if it's a 208 (which I don't know what I have yet honestly) and 75w90 in the axles.

Issue I have - I hate having excess fluids laying around. I'm about to do my truck's transmission & rear end. It takes Castrol Syntorque for the transmission. Problems if I run this in the Blazer's transmission?

 

[obijuank5]

I'm pretty sure you can run almost anything in an sm465. Quality oil wont hurt. If you have an aluminum case transfer case, it does require atf.

 

[wasted wages]

Good info here :

http://www.novak-adapt.com/knowledge/transmissions/manual/sm465

You can use 50wt motor oil, just make sure it's a straight weight 50 - non detergent.
I've used Royal Purple 50wt and was really happy with the way it shifted...

 

[4thgenceli]

Cool beans.

Got it sealed up. Ended up a small bead of RTV and called it good. Crap thing now is that I have the motor dropped back in it looks like the front diff started leaking...lol. oh the joys of 30 year old beasts. Guess it's a good thing I was planning on changing front and rear diff fluids!!

 

[wasted wages]

That's the good/bad thing about changing old fluids.. It's good to put in fresh fluids, but in doing so, the new stuff tends to flush out all the crud that may be preventing seals and gaskets from leaking.

I'm a firm believer that old automatic transmissions are better left alone if they haven't been serviced regularly.
flushing out the clutch dust mixed in the fluid maybe the only thing keeping things sealed internally...

I'm sure there are many that won't agree, but I'll take my chances and just top off a low level. My power glide in the '68 C10 is a perfect example, when I got the truck, the P/O just changed the fluid.. everything was nice and dry under the truck, so it had not been leaking. After about 3 months of driving it ( very few miles ) I can't stop all the leaks. ..if I don't drive the truck every few days, the torque converter drains, the pan overfills and fluid pours out of the shift selector shaft seal... I've double sealed it, and it still drips. .