G80 - Any good in 14SF?

[df2x4]

posi additive

That's probably a big part of your problem. There's a GM TSB that's been floating around for a long time that states not to use any friction modifier with our G80s. I made that mistake in my red truck for a while and had a really similar experience. I had it drained and replaced with ACDelco standard GL5 80W-90 and ran it for a while and the G80 is working again. It's still a crappy unpredictable 10 bolt G80 but getting rid of the friction modifier brought it back to life.

I can't find the link to the actual GM TSB but I found a post on ChevyTalk where @someotherguy quoted the relevant info.

https://www.chevytalk.org/fusionbb/showtopic.php?tid/256237

 

[98chevy2500SS]

LoL if it's a 3.73 unit I'll gladly trade you for my 10 bolt non-G80 axle

It sure is 3.73! lol, that's what I liked about this truck when I bought it, didn't want 3.42's like my 98 when it was a half ton.

The G80 should help when I plow snow with it, but I did fine with my 98 that doesn't. Oh well, I'll try it sometime here to see if it will be something that I like, or won't like.

 

[DerekTheGreat]

It sure is 3.73! lol, that's what I liked about this truck when I bought it, didn't want 3.42's like my 98 when it was a half ton.

The G80 should help when I plow snow with it, but I did fine with my 98 that doesn't. Oh well, I'll try it sometime here to see if it will be something that I like, or won't like.

Well please don't like it haha. When you end up hating it, remember this post and if I haven't already tripped over one I'll gladly take it off your hands once we agree to a price & what not.

 

[someotherguy]

@df2x4 even when you show folks the TSB straight from GM with that very clear wording (the section that I bolded and underlined) some will still argue with you about posi additive.

Richard

 

[Schurkey]

That's probably a big part of your problem. There's a GM TSB that's been floating around for a long time that states not to use any friction modifier with our G80s.

Thanks for that. I had no idea.

I've got gallons of gear lube here--mostly Amsoil--that is advertised as having the posi additive already in the mix. That's what I filled the axle with.

AMSOIL Long Life Synthetic Gear Lube is compatible with most limited-slip differentials. If limited-slip differential chatter occurs, add AMSOIL Slip-Lock® friction modifier additive.​

Now I get to buy more gear lube that doesn't have Posi additive...and I'm not sure where to get it aside from a GM Stealership.

Recommendations?

 

[df2x4]

Thanks for that. I had no idea.

I've got gallons of gear lube here--mostly Amsoil--that is advertised as having the posi additive already in the mix. That's what I filled the axle with.

AMSOIL Long Life Synthetic Gear Lube is compatible with most limited-slip differentials. If limited-slip differential chatter occurs, add AMSOIL Slip-Lock® friction modifier additive.​

Now I get to buy more gear lube that doesn't have Posi additive...and I'm not sure where to get it aside from a GM Stealership.

Recommendations?

You're welcome!

I buy mine from Amazon, ACDelco part number 10-4051. Here's a link.

https://www.amazon.com/gp/product/B007Q10F3S

 

[Schurkey]

Interesting:

It is for use in passenger cars only, and is not intended for use in trucks.​

Which seems to be the opposite of what the GM bulletin specifies.

 

[df2x4]

Interesting:

It is for use in passenger cars only, and is not intended for use in trucks.​

Which seems to be the opposite of what the GM bulletin specifies.

Yeah I'm not sure why that's written on the bottle, it's the right stuff though. I double checked with the parts department at my local dealer. It's what superseded the part number listed in that TSB.

 

[Urambo Tauro]

Could that note be in reference to large tractor trucks? ...and grouping pickup/"light duty" trucks with passenger cars?

 

[df2x4]

Could that note be in reference to large tractor trucks? ...and grouping pickup/"light duty" trucks with passenger cars?

That was my line of thinking as well, who knows though.