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Limited slip differential fluid question

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Old Sep 5, 2016 | 07:56 AM
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78 & 87 Super Cab's Avatar
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Question Limited slip differential fluid question

When "topping off" a limited slip axle (like adding less than 12 ounces or so of fluid) would I have to add the friction modifier additive as well? I can see having to do it, like when doing a drain and refill.

The axle code in My 1994 F150 according to the door sticker is H9. Looking at the rear cover, i see no tag saying use limited slip additive, the tag on it says the following:

S847F

3L55 88 3K25
 
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Old Sep 5, 2016 | 11:24 AM
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Add it in proportion to the amount of regular oil you added.

To be fair, it's pretty likely your limited slip is worn out anyways, so it wouldn't matter.
 
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Old Sep 5, 2016 | 05:29 PM
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The 3L55 means it is a limited slip 3.55. They only take 4 ounces of the friction modifier during refill, so it's not a lot. I'd just top it off with a gear oil for limited slips or even the regular stuff, it probably doesn't matter.

If you're having to add fluid, check for leaks.
 
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Old Sep 5, 2016 | 05:55 PM
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Thanks for the info, Mine is not leaking and level is full.Will use this for future reference
 
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