what transmisson fluid to use in a th350 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

shipma2 · 09-28-2012, 07:59 PM

what transmisson fluid to use in a th350 transmisson ? will dexron work in it or should i use something else? also my transmisson leaks like a syfe i think it maybe the pan seal, but the kicker is the th350 is behind a 454 which worries me, i have heard horror stories about them being prone to failure behind a 454. any tips or suggestions for my 78 k10 would be greatly appreciated thank you

mopar346 · 09-28-2012, 08:44 PM

Dextron or any of the derivative should be fine. My fix suggestion is fix what is leaking immediately, then I would probably find a 400 to put in it. A 350 coudl be built to live fine behind a 454 but it will cost a little. The other fact is jsut saying it a 454 doesn't really clarify things. A fire breathing 500 horse 454 is gonna make small work of it, a lame (no offense) smog 454 wont give it any trouble. AND it depends on what's inside of your current 350, I think there are different drums that hold a different number of clutches for more strength. I know this is the case with many tranny and I believe 350s as well, but I could be wrong, remember I'm a Mopar guy.

cory d · 09-28-2012, 09:25 PM

stock 454?

meter swinger · 09-28-2012, 09:36 PM

I have done my own tranny gaskets in the past but honestly, its a pain in the a$$ working undernearth a tranny unless you have a lift.
I have a tranns guy that will do a filter, pan gasket, and fluid on a 350 for 65 bucks. Worth every penny.
Check the side of the unit to see if your leaking out of the shifter area or where the cable goes in.
Find a reputable trans shop. If you need a rebuild on your 350 it probabky wont be much more to swap in a 400.
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clinebarger · 09-28-2012, 09:51 PM

The number 1 & 2 causes of transmission failure are low fluid level, As mopar346 said....Fix the leak.

A TH350 can be built to handle your 454 mild to wild.
If you didnt have the existing TH350 rebuilt....It probably needs it anyway.

shipma2 · 09-29-2012, 06:22 PM

it is stock, from a 1973 i belive, the motor is not original to the truck as the vin states a 350 4 barrel, though i have reason to belive four or five motors and transmissons have been in it lol

09-28-2012, 07:59 PM	#1
shipma2 Registered User Join Date: Aug 2011 Location: manti utah Posts: 95	what transmisson fluid to use in a th350 what transmisson fluid to use in a th350 transmisson ? will dexron work in it or should i use something else? also my transmisson leaks like a syfe i think it maybe the pan seal, but the kicker is the th350 is behind a 454 which worries me, i have heard horror stories about them being prone to failure behind a 454. any tips or suggestions for my 78 k10 would be greatly appreciated thank you

09-28-2012, 08:44 PM	#2
mopar346 Registered User Join Date: Jan 2011 Location: Quincy, FL Posts: 533	Re: what transmisson fluid to use in a th350 Dextron or any of the derivative should be fine. My fix suggestion is fix what is leaking immediately, then I would probably find a 400 to put in it. A 350 coudl be built to live fine behind a 454 but it will cost a little. The other fact is jsut saying it a 454 doesn't really clarify things. A fire breathing 500 horse 454 is gonna make small work of it, a lame (no offense) smog 454 wont give it any trouble. AND it depends on what's inside of your current 350, I think there are different drums that hold a different number of clutches for more strength. I know this is the case with many tranny and I believe 350s as well, but I could be wrong, remember I'm a Mopar guy.

09-28-2012, 09:25 PM	#3
cory d Registered User Join Date: Dec 2011 Location: Arlington WA Posts: 1,728	Re: what transmisson fluid to use in a th350 stock 454? __________________ GMC C15 355 SM465 3.73 80 C10 cruiser build thread 79 short stepside crew cab. big and ugly. build thread

09-28-2012, 09:36 PM	#4
meter swinger Registered User Join Date: Apr 2009 Location: Kennewick WA. Posts: 1,437	Re: what transmisson fluid to use in a th350 I have done my own tranny gaskets in the past but honestly, its a pain in the a$$ working undernearth a tranny unless you have a lift. I have a tranns guy that will do a filter, pan gasket, and fluid on a 350 for 65 bucks. Worth every penny. Check the side of the unit to see if your leaking out of the shifter area or where the cable goes in. Find a reputable trans shop. If you need a rebuild on your 350 it probabky wont be much more to swap in a 400. Posted via Mobile Device

09-28-2012, 09:51 PM	#5
clinebarger Senior Member Join Date: May 2009 Location: Fort Worth, TX Posts: 6,370	Re: what transmisson fluid to use in a th350 The number 1 & 2 causes of transmission failure are low fluid level, As mopar346 said....Fix the leak. A TH350 can be built to handle your 454 mild to wild. If you didnt have the existing TH350 rebuilt....It probably needs it anyway.

09-29-2012, 06:22 PM	#6
shipma2 Registered User Join Date: Aug 2011 Location: manti utah Posts: 95	Re: what transmisson fluid to use in a th350 it is stock, from a 1973 i belive, the motor is not original to the truck as the vin states a 350 4 barrel, though i have reason to belive four or five motors and transmissons have been in it lol



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