grape Juice?

[Wally]

A while back discussions on the Grape juice and an aftermarket suitable rear-end fluids were common.
Did anyone ever get the full skinny on this stuff?
I ask because I had four quarts left over from the Duramaxes and wanted to use them in the 96 Ford. It has a limited slip axle and Ford says to use 4 ounces of friction modifier. One of the hot topics about the Grape Juice was if another synthetic fluid were used would a friction modifier have to be used.
Did the GM stuff not require any because it was already a property of the fluid or did the GM locking diff just not need it?
I know GM fluid in a Ford! Hey I payed 10$/qt for this stuff and I need to use it for something.

[Gbenzx01]

Well Wally,
I can easily see why no one has jumped to answer your ques.
The first time I ever smelled the stuff I couldn't wait to get it away from my little D/A!
It needs no modifier & is made by texaco I thimk so you may find joy comparing chemicals used at their website if Gergg at lubespecialist or George Morrison at avlube cannot first help.
My own feel is that I would not dare unless I could be certain the makeup would match. :confused:

Gben

[a64pilot]

Wally,
If you want to use the Grape Juice in a Ford go ahead it shouldn't hurt anything but your wallet. Where did you get it for $10. I don't remember what I paid, but I'm sure it was more than that.
The reason we don't use a friction modifier in the GM trucks is that we are not positive traction, we're lockers. The diff is as I see it is that positive traction tries to keep one wheel from spinning, while a locker like ours feeds power to the non spinning wheel after spinning occurs. The locker will allow a greater torque split between the wheels than a positive traction unit will though, so don't think a locker is inferior. IMHO a positive is better for a high horsepower car on a drag strip etc. while a locker is better for a truck tring to pull a trailer in mud where one wheel may have much better traction than the other.

[MadDuraMax]

The G80 does use clutches in order to activate the locking pawl. Then centrifical force to unlock it over 15MPH or so. Somewhere I posted a letter from GM stating that they no longer want to recommend a friction modifier because of increased chatter and clutch wear. Eaton only recommends it's use in their aftermarket variant.

The "grape juice" is comparable to most any other high quality synthetic and can be used anywhere it meets or exceeds the service recommendation. It does not contain a friction modifier.

Mark

[Wally]

Thanks Mark,
That was the info I was looking for. I have put it in the Ford without any friction modifier for now. What are the signs of needing a modifier?
As far as price. When a dealership does warranty work on the Eaton the mechanic usually draws out 5 qts because the official capacity is 4+ qts. Very seldom is the any of the fifth qt needed so quite a few line mechanics end up with several unopened bottles under their work bench. You just gotta know who to ask at the dealership.

[MadDuraMax]

Wally,

First sign of needing to add a friction modifier is the mfgr's reccomondation. On my d@dge with an Auburn Gear it will chatter or "pop" when making low speed cornering. If this occurrs when the fluid is changed and a friction modifier is added then the culprit is normally clutch pack preload and or adjustment.

In the G80, I've been running straight Mobil 1 without even a hint of problems.

Mark