Rear differential gear oil additive

[txab]

Not being difficult, but it's no different than the confusing language about Dexos oil usage...it doesn't say the gear oil can't be for an LS, only that adding friction modifier is bad.

 

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Which if the gear lube has a friction modifier in it, then it's an additive above gear lube with no modifier

[sdeeter19555]

Which if the gear lube has a friction modifier in it, then it's an additive above gear lube with no modifier

But does it? It's my understanding that synthetics don't incorporate friction modifier, but they are approved for limited slip differentials without further additives?

 

Again, just because the lube from GM states it's for the G80, doesn't mean friction modifier is not already in there as part of the formulation for that specific differential...

 

I've ran non-friction modified gear oil in clutch type limited slips...that causes chatter, it doesn't cure it.

 

Again, I think this is good discussion.

 

You can take that explanation from GM either way...either it can't have a fluid with friction modifier or you're not supposed to add friction modifier to the gear oil (as it's formulated).

 

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[redvett]

GM uses Synthetic Gear Lube in all trucks regardless of having G-80 or not since the late 80's. So why not just use Synthetic Gear Lube in both front & rear especially if you reside in cold winter climates. GM recommends using Synthetic Gear Lube in front Diff. for very cold temperature's, this was a TSB many years ago.

[intheburbs]

That is a good vid. Crazy that some of the other 4x4 couldn't make it up the hill. Is tjey g80 that much better than the competitors locking diff or was than an exaggerated?

 

 

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I wouldn't necessarily say it's that much better, but it is pretty good. It's automatic, and passive, so the driver doesn't have to do anything extra to make it work/engage.

 

The downside to the G80 is that it doesn't like doing peelouts/burnouts/donuts. If you drive like a teenage boy, you'll probably break it. All three of my trucks have the G80. I've taken them offroad (Moab, UT, Colorado, etc), tow heavy trailers and drive fast. I've never broken one over about 450,000 miles of driving (the total of the odometer reading on my three trucks past and present).

 

This is what kills a G80:

 

 

[sdeeter19555]

I run 75w140 Amsoil SVO, and had my G80 work well the two times I needed it today. So, after nearly 90k on the SVO, it doesn't seem to have negatively affected the G80 operation.

 

Just throwing that out there...

 

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[txab]

[Z45]

Why a friction modifier is used in a Limited Slip

 

 

Chatter is essentially the build-up and release of energy between the differential clutch packs in a limited slip differential during operation. This phenomenon often occurs when torque is transferred between the clutches or when rotational speeds change. During the stick-slip phase, energy is built up to a point where contact between the clutch plates change between static friction (stick) and dynamic friction (slip), resulting in noticeable vibrations. It is this vibration that causes an audible chatter or ratcheting to be heard within the differential. While certainly an annoying characteristic, there is typically no mechanical damage occurring to the differential. It is most often noticed in parking lots or slow driving while turning where the outside wheel turns faster than the inside wheel.

In an effort to control this chatter, friction modifiers are often used. These additives result in a smoother transition between the two states of friction: static and dynamic. Static friction occurs when the clutches physically lock together, while dynamic friction occurs as the clutches are slipping, ergo Limited Slip Differential.

 

 

 

[Gurrzt]

If you do any hard aggressive driving use straight 140W dino oil and change every 50k

[Jh8473]

Don't use Acdelco 10-4016 70w 90, caused my rear end to start locking up during turns.

[diyer2]

Does the year of the truck make a difference or are all G80's the same?

[Black02Silverado]

Does the year of the truck make a difference or are all G80's the same?

It is my understanding that the G80 is the same from the day it was introduced.

[Colossus]

There have been minor changes over the years, but I'm pretty sure the fluid requirement stays the same. No add packs!

[repairman54]

Yep no LS additives just run a synthetic gear oil.

G80 in my '89 S blazer & '99 Yukon both lasted over 180k miles. Factory fill on those trucks was NOT synthetic. In fact GM shop manual specified changing rear diff. oil at 30k miles. on my Yuk . It was dark and very used looking at 36k when I got the truck and changed it.

G80 is standard when truck is built with factory towing package.

As prev. said if you don't play teenage wheel spin games the unit will last a long time. That's what Camaros are for.