Grape Juice

[John R]

I have A 2003 Chevy 2500HD with the G80 locker axle,

and was wondering if the synthetic axle oil that GM sells

that smells like grape juice is OK for heavy duty use?

I tow A 12000 LB trailer.

Also do you need any additive for the locker with this fluid?

[BDBWTE]

With the Gov lock you don't need Synthetic's or additives. You should have a 14 bolt FF rear axle manf. by AAM. I would run Straight 80W or a 75W-90. It's up to you you could run A synthetic but if your like me the cheapest most effective way is the way to go.

[422 SS]

You dont need any additives.Your truck has a 16,000 lb tow rating,Im sure that the stuff GM uses is just fine.Its also good for 250,000 miles.Your truck doesnt have a 14-bolt.The Dmax And 8.1 come with a different axle with a 11.5 ring gear.Im not sure what its called but its not a 14-bolt.The 14-bolt has a 10.5 ring gear.Your new truck should be fine for a very long time.

[marcski]

the grape juice is what the 2500HD's with the G80 come filled with. no additive necessary. takes almost 4 quarts. if you tow alot, you can use a 75w-140 but most non commercial go with the 75w-90 grape juice

[1BADHD]

Mine didnt come with grape juice. When I changed mine it came out a awfull smelling yellow oil. And I am not sure but, one of the diffs do REQUIRE synthetic. I thought it was the rear. Better read your manual.

[BDBWTE]

You dont need any additives.Your truck has a 16,000 lb tow rating,Im sure that the stuff GM uses is just fine.Its also good for 250,000 miles.Your truck doesnt have a 14-bolt.The Dmax And 8.1 come with a different axle with a 11.5 ring gear.Im not sure what its called but its not a 14-bolt.The 14-bolt has a 10.5 ring gear.Your new truck should be fine for a very long time.

Didn't read this signature with the DMAX part. Good catch. I don't know what AAM wants you to put in that carrier.

[Black02Silverado]

With regular maintenance it will last a long time. Synthetic will not hurt a thing but can add a little benefit of running cooler if you do a lot of hauling and towing. Yea it cost more but your truck is a serious investment that if you can do a little extra why not. We all add after market stuff all the time, so why not go the extra mile where it counts. Some see performance improvements and some don't.

[JimWilson]

"Grape Juice" is synthetic, so synthetics are definitely not a problem.

 

If you're going to tow something that heavy fairly often you might want to go from the 75-90 that's stock to 75-140. GM recommends that you do it if you're going to tow a lot, or use it like a work truck.

[jbplock]

Dittos to what Jim said… There has been condiderable discussion on rear diffs

and lube over at TheDieselPage forum. The following is a quote from a post by

TxDoc who wrote to Eaton regarding diff lubes and service.

(I’m relatively new to posting here so my apologies if this is not allowed).

 

Two bits of info from Eaton I received on the locking rear end(G80)were:

1--

"GM introduced the new body style in 1998. At the same time they upgraded

the differential and changed to a synthetic lube. The G80 is specifically

designed to give ultimate performance with this lube, and the lube contains

special additives that help reduce slip stick that occurs between the

clutches. the GM synthetic lube typically runs about 100+ degrees cooler

than mineral base lube, which is better if you do allot of towing or heavy

hauling. I would recommend that you stay with the GM synthetic, not Mobil 1.

If you don't tow or haul you could use the pre 1998 mineral lube without

degrading performance of the differential. this would be a cheaper option

but require more lube changes. "

"Axle tolerances of the 1/2 ton trucks are very tight. The recommended

procedure was to change lube after 500 miles of heavy towing, which would is

considered a break in period. This breaking period generates high heat

conditions in the axle which was found to degrade the synthetic beyond the

point of mineral lube. After the 500 mile lube change, the axle is broke

in and does not generate the high heat. If you use GM synthetic after the

break-in period, it can be considered "lube for life", although some say to

change it at 40,000 - 50,000 mile intervals."

"If you don't tow, don't worry about the oil change as it a waste of money."

 

"If your truck is pre 1998 or the old style, it comes with mineral lube. IN

that case you need to stay with mineral because the seals are designed to

work with it. If you changed from mineral to synthetic you'll cause your

seals to swell and eventually leak. It's ok to go from synthetic to

mineral because you won't cause swelling. many of your stop leak

chemicals effect seals in this manner, resulting in a short term fix but a

long term problem."

2--

and on service

 

"From Mr. Ralph Holmquist of Eaton, the maker of the locking differential:

"The maintenance schedule for the rear axle was developed by American Axle &

Manufacturing and GM truck based on multiple tests. The Eaton locker does

not require additional maintenance nor does it add heat to the lube. The

lube will darken due to the carbon wear on the clutch surfaces, much the

same as a disc brake pad & rotor. This does not damage axle components such

as seals or bearings. However, a new axle can produce excessive

temperatures (plus 350 degrees F) due to the ring & pinion breaking in that

will break the lube additives down. Avoid high loads, trailer towing and

high speed extended driving during the initial break in of the vehicle.

After the break in period axle temps will level at a much lower figure.

Lube changes are a good idea because the additives are replenished and

contaminates such as casting sand are eliminated. The axle is filled at the

factory with a synthetic 75w90 GL5 rating made by Texaco under part # 2276.

The GM service # is 12378261. This is the only lube we have done extensive

testing with to insure locker compatibility. The only negative to using one

of these other lubes is an increased potential for clutch chatter. This

really doesn't hurt anything and can be corrected by changing the lube. I

noticed in the latest GM owners manual the term "or equivalent" when

referring to the lube specification. Look for a GL5 rating on the bottle to

make sure the ring & pinion, seals & bearings are protected. Limited slip

additive is not needed."

The following information outlines the type of

rear axle lubrication utilized in GM Truck axles.

I. Fluid Type

II. The 1500, 2500 and 3500 GMT 800 Trucks utilize SAE 75W-90 Synthetic Axle

Lubricant. The GM part number is 12378261 and the specification is 9986115.

¨ Note: the recommended lube for HD trailer towing is a 75W-140 Synthetic Gear

lube, part number 12346140.

III. Inspection/Change Frequency

¨ The 1500 and 2500 GM Trucks recommend rear axle fluid level checks every

7500 miles. Fluid should be added as needed.

¨ Under heavy duty trailer towing conditions the lube should be changed after the

first 500 miles of towing. This is due to the extreme heat generated on break-in of

the hypoid gear set."