Front diff need modifier?

[Astro]

Hey guys, gonna change the fluid in my front diff. 96 k1500. Does the front need the Ac Delco additive?

Also, how much additive per quart?

Thanks y'all!!!!

 

[454cid]

It's an open differential, all you need is gear oil.

 

[evilunclegrimace]

Straight GL-5 no additive

 

[Astro]

Gotcha, thanks guys, I appreciate it!

How about the rear? I've got the 14 bolt, 9.5" SF G80. Was told this one takes the additive.

If yes, how much per quart on this one?

 

[fancyTBI]

Gotcha, thanks guys, I appreciate it!

How about the rear? I've got the 14 bolt, 9.5" SF G80. Was told this one takes the additive.

If yes, how much per quart on this one?

It does not take additive. The G80 does not need a friction modifier like a true LSD does. Use regular 80W90

 

[Astro]

It does not take additive. The G80 does not need a friction modifier like a true LSD does. Use regular 80W90

I appreciate it man.

Could you humor me and explain to me why it doesn't? I keep getting differing responses to this question, but if I understood the reason, it would help me a lot.

I'm guessing it has to do with the way it locks, but I'm not sure.

 

[evilunclegrimace]

A G80 locking differential does have clutches but adding additional friction additive to the differential housing causes them to loose their coeffeient of friction and slip when they are not supposed to.

 

[someotherguy]

I appreciate it man.

Could you humor me and explain to me why it doesn't? I keep getting differing responses to this question, but if I understood the reason, it would help me a lot.

I'm guessing it has to do with the way it locks, but I'm not sure.

Because people keep calling it the wrong thing. It's a locker, not a "posi" and this one gets beat into the ground even after you show some people the TSB from GM that says DO NOT use additive in the Eaton Gov-Loc unit as it can cause improper operation.

G80 is just an RPO code, it does not apply to just one specific piece of equipment. In a GMT400 truck like ours it means the Eaton Gov-Loc. In many car applications it does indeed mean a positraction unit. This is where the confusion starts.

Richard

 

[df2x4]

These guys already covered it, no friction modifier or additives required for anything that came stock in these truck axles. GM actually released a TSB years ago stating not to use any modifiers or additives with the G80 lockers, and I've personally fixed one that was misbehaving by draining and refilling with no additive.

FWIW, this is the current recommended GM oil for the G80 lockers, part number 88900401. Confirmed by a GM engineer and parts counter guy, @MrPink.

www.amazon.com/Genuine-88900401-75W-90-Synthetic-Lubricant/dp/B00BK7LXGM

 

[GoToGuy]

As " someotherguy" stated above, the RPO code text calls it a " positraction differential" , Remember the code is a general description not exact definition. It takes the RPO code and parts book for that year to know what type of positive traction control is installed.
Just as GM has 3 or 4 different " eng oil cooler " designs yet they are all the same RPO code. The year and eng determined which was installed.