1970 Z28 4 speed fluid question

[VoodooChildZ28]

Hello going to replace all fluids when new radiator/electric fan kit arrive what would be appropriate fluid for the Muncie and if you want to save me some more time what gear oil for the posi ? Looks like it’s leaking so I want to replace the gasket and fluid. I’m a Royal Purple fan but open to any good brands Amsoil, Lucas etc. thanks all God bless

 

[checkmate201]

Driven Oil is great for Muncie and is GL-4
GO 80W-90 Conventional GL-4 Gear Oil
https://www.drivenracingoil.com/go-80w-90-conventional-gl-4-gear-oil.html

 

[Lowend]

Redline MTL for the Transmisson. That stuff is magical

https://www.redlineoil.com/mtl-75w80-gl-4-gear-oil

 

[VoodooChildZ28]

Thank you gentlemen. What about for the posi?

 

[Lowend]

For the rear, Redline GL-5 in 75W90
Already has the friction modifiers in it for the Posi
https://www.redlineoil.com/75w90-gl-5-gear-oil

 

[VoodooChildZ28]

Fantastic advice thank you. Summit has it. Now for the Muncie what’s the captacity and of the posi? Thanks I’m advance

 

[COPO]

Forget about capacity. Get 2 bottles for each the trans and posi and you’ll have some leftover. Fill both cold to the below the threads so when you stick your pinky finger in the hole, you get fluid on the tip of your finger.
Check when hot and fill to the bottom of the threads or when it starts to spill out of the fill hole. For both I use non synthetic GM 80w90 gear oil and with the posi I add 1 bottle of GM posi additive.

 

[Gary S]

I use Amsoil MTG in al my manual trannys. It makes the shifts smoother than you ever dreamed they could be. I have an old '81 Chevy pickup with the Muncie truck 4 speed. They shift like a pig new and don't improve with age. This one from new was very difficult to get out of 2nd and to 3rd. After suffering with it for 20 years, I switched the lube to Amsoil MTG. It now shifts like butter with no more of that hangup in 2nd. That convinced me to put the same stuff into my Camaro Muncie. The Camaro always shifted nice, and with Amsoil, it might be even a bit better.
Amsoil MTG is specially formulated for old Manual trannys. It is GL4 rated for trannys.

 

[VoodooChildZ28]

Thank you boys. This bastard does not want to get into 3rd gear and praying the new trans fluid helps, as well as a gasket fixes the posi leak. I almost bought 4 quarts trans and 2 posi so thanks for the help! I’ll get two of each and pray this cranky tranny will find 3rd haha as well as stop the small leak

 

[COPO]

The additive should only be this size.

If it won’t go into a gear then do a neutral alignment on the shifter.

Gauge pin