transmission oil change

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Empire402

Junior Member
Joined
Jun 1, 2022
Posts
6
Reaction score
2
Location
Canada
First Name
John
Truck Year
1984
Truck Model
C30
Engine Size
350
Any Dex3 fluid will work; Dex6 full synthetic is backwards compatible but not necessary. If your filter is the cloth variety (probably is, if you're having delayed engagements cold only) then toss it in the trash and install a screen style filter. Never use the cloth type - they suck. Use a regular composite style pan gasket (no cork or rubber - they both leak) and no RTV on the pan, gasket, or mating surface.
Just wondering if you had any recommended brands/part numbers for the fluid, screen style filter, and composite style pan gasket? I need to service the TH350 in my 81 K10 soon and just want to get the right parts and would appreciate your input.
 

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
5,444
Reaction score
8,676
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
time to change the transmission oil and filter, any suggestions??
I have a suggestion. Put a drain plug in the pan.Drain and fill the transmission pan at oil changes. Yes it will only by a 4 qt swap but 4 times a year,and your transmission will always have relatively fresh fluid
 

NickTransmissions

Supporting Member
Supporting Member
Joined
Aug 3, 2023
Posts
412
Reaction score
851
Location
Las Vegas
First Name
Nick
Truck Year
1987
Truck Model
R10
Engine Size
350
Just wondering if you had any recommended brands/part numbers for the fluid, screen style filter, and composite style pan gasket? I need to service the TH350 in my 81 K10 soon and just want to get the right parts and would appreciate your input.
Ditto what @Ricko1966 said; check Mr Gasket for a rubberized gasket with steel inserts, think they make one for the TH350. If you cant find it, composite gaskets are fine but DO NOT use cork or regular rubber as they both leak. Fluid is your choice. Trans fluid is heavily regulated so any DexMerc certified fluid will be fine. Same for the screen style filter.
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,693
Reaction score
6,869
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
Ditto what @Ricko1966 said; check Mr Gasket for a rubberized gasket with steel inserts, think they make one for the TH350. If you cant find it, composite gaskets are fine but DO NOT use cork or regular rubber as they both leak. Fluid is your choice. Trans fluid is heavily regulated so any DexMerc certified fluid will be fine. Same for the screen style filter.
my favorite is the fluid claiming to meet or exceed the specs for Mercon/Dexron III and Mercon V and Dexron VI AND Mercon LV and Dexron ULV
 

LocoLocal

Full Access Member
Joined
Sep 18, 2022
Posts
97
Reaction score
131
Location
Just east of West by God
First Name
Rob
Truck Year
1979
Truck Model
C10 Silverado
Engine Size
5.0
Any Dex3 fluid will work; Dex6 full synthetic is backwards compatible but not necessary. If your filter is the cloth variety (probably is, if you're having delayed engagements cold only) then toss it in the trash and install a screen style filter. Never use the cloth type - they suck. Use a regular composite style pan gasket (no cork or rubber - they both leak) and no RTV on the pan, gasket, or mating surface.

You're welcome...Check your area for a local Transstar distributor/OTC retailer. If one is present, they will have everything you need and possibly for cheaper than Rock Auto when shipping is factored into the total price.

ETA: If you still have delayed engagements only when cold after the filter/fluid change then I'd suspect excessively worn pump stator bushings leading to converter drainback...

Ok, so I changed the fluid and put a new filter in. Now I am having the opposite problem: instead of failing or being slow to engage, it feels like its jumping into gear too hard when I shift, both from a cold start when parked and when driving down the road going into higher gears.

Any advice? Maybe (hopefully) I was just used to the sloppy shifts with the old fluid and filter?

Thanks.
 

Forum statistics

Threads
44,156
Posts
950,542
Members
36,268
Latest member
JUKA
Top