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Differential fluid additive. Do I need it?

This is a discussion on Differential fluid additive. Do I need it? within the Technical / Maintenance forums, part of the General Discussion category; Do I need additive for front and rear differentials? I have a 1989 K3500 with a 454....

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    Differential fluid additive. Do I need it?


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    Do I need additive for front and rear differentials? I have a 1989 K3500 with a 454.

  2. #2
    GMC RULZZ NEUMANNZZ's Avatar
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    Re: Differential fluid additive. Do I need it?

    no.
    O2 GMC RCSB 4.8L V8 AUTO 3.73's
    rebuilt/beefed up 4L60E(at 43,000miles)
    Matching Ninja 500r


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    Registered User bowtie44s's Avatar
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    Re: Differential fluid additive. Do I need it?

    Do you have limited slip or open rear end?
    Jeff

    '88 chevy k3500 aluminum head 454
    NV 4500

    '84 chevy short bed dana 60 14bolt ff 383 stroker
    44" boggers (rear) 44" tsl (front) hydraulic assist
    welded front and rear 5.13 gears
    th400 np205 twin stick -SOLD-

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    Re: Differential fluid additive. Do I need it?

    only if someone did aftermarket work

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    Re: Differential fluid additive. Do I need it?

    Im not sure. How could I tell if its standard or limited slip. I dont know if anyone worked on it or not. I forgot to post its 4x4.

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    Registered User bowtie44s's Avatar
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    Re: Differential fluid additive. Do I need it?

    The front is open or you'd know it, don't use additive. When the rear spins do one or both spin? You can jack both back wheels up put tranny in neutral and spin one wheel, if both spin the same way you need additive, if one spins forward and one spins backwards it's open.
    Jeff

    '88 chevy k3500 aluminum head 454
    NV 4500

    '84 chevy short bed dana 60 14bolt ff 383 stroker
    44" boggers (rear) 44" tsl (front) hydraulic assist
    welded front and rear 5.13 gears
    th400 np205 twin stick -SOLD-

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    Re: Differential fluid additive. Do I need it?

    Look in the glove box and see if the rpo option code label is still present and/or readable. If the truck has the original rear axle and the label in the glove box has a G80 code listed it should have a locking or limited slip rear axle in it. I always thought that the G80 option meant locking differential but recently I did diff fluid change on my brother's 2000 Chevy K3500 OBS truck and my own 1998 k1500 and was surprised to find that the 2000 K3500 had a limited slip type rear diff in it unlike the locking rear diff in my 98 k1500. I used Mobil 1 LS 75w90 synthetic in both trucks and did not need diff additive as Mobil 1 LS fluid has limited slip additive already in it. If you have the G80 option and use regular gear oil then you should add the limited slip additive.

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    Registered User bowtie44s's Avatar
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    Re: Differential fluid additive. Do I need it?

    Quote Originally Posted by rabristol View Post
    I have a 1989 K3500 with a 454.
    Does yours have the dana 70 rear or 14 bolt? I thought most had 14 bolts but my 88 k3500 454 has a dana 70.
    Jeff

    '88 chevy k3500 aluminum head 454
    NV 4500

    '84 chevy short bed dana 60 14bolt ff 383 stroker
    44" boggers (rear) 44" tsl (front) hydraulic assist
    welded front and rear 5.13 gears
    th400 np205 twin stick -SOLD-

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    Resident Dick Quyonmob's Avatar
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    Re: Differential fluid additive. Do I need it?



    Quote Originally Posted by GM TSB
    LOCKING DIFFERENTIAL LUBRICANT (SERVICE INFORMATION) #91-4-109
    SUBJECT: LOCKING DIFFERENTIAL (G80) LUBRICANT - (SERVICE INFORMATION)
    VEHICLES AFFECTED: ALL LIGHT TRUCKS EQUIPPED WITH G80 REAR AXLE ALL YEARS
    Some light duty trucks equipped with locking rear axles (G80) may exhibit rear axle chatter, especially when turning a corner from a stop.
    This condition of alternate engagement and disengagement of clutches in differential assembly is usually caused by contaminated axle lubricant.
    To correct this condition, drain and refill the rear axle with SAE 80W-90 GL5 (P/N 10950849).

    The use of any additive in locking rear axles (G80) is not recommended. Rear axle additives are designed for use in limited slip differentials which are normally installed in cars. All light duty trucks equipped with RPO G80 make use of a locking differential and the use of additives will delay the engagement of the locking mechanism and may decrease axle life.

    VEHICLES/COMPONENTS INVOLVED: ------------------------- ---- Some light duty trucks equipped with locking rear axles, RPO G80.
    SERVICE PARTS INFORMATION:
    Part Number Description ----------- ------------------ 10950849 Lubricant, Rear Axle (1 litre)
    Parts are currently available through CANSPO.
    WARRANTY INFORMATION:
    As specified in Light Duty Truck Maintenance Schedules, locking rear axle fluid drain and refill is required owner maintenance at the first engine oil change. Failure to drain and refill the rear axle as specified may contribute to a later axle chatter condition. Refer to the appropriate Light Duty Truck Maintenance Schedule or service manual, section OB, for further details on change intervals.
    General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
    Copyright General Motors Corporation. All Rights Reserved.

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    Re: Differential fluid additive. Do I need it?

    Automatic Locking Differential Lubricants.

    From Michael Asmussen, Torque Control Products Division of Eaton Corp.

    "We recommend the following lubrications for our GM truck locking differentials:
    1)Texaco 2276; Synthetic 75 W90; Gm Part # 9986115
    2)Texaco 9622; Mineral based 80W90; GM Part # 9985290
    3)Texaco 2080; Synthetic 75W140 (heavy duty applications); GM part # 9985991

    Note - All of the above lubes are preblended with friction modifier. No additional modifiers are necessary .
    As far as other lubes are concerned, any standard GL 5 lube will work, but the units perform optimally with the three listed above. "


    IMO if you use the GM fluid you won't need diff fluid additive (friction modifier) but if you use diff fluid without the preblended friction modifier you may need to put additive in to eliminate chatter or noise.
    I guess the safe bet would be to change the fluid and see how the diff works. You can always put additive in later if neccesary....

  11. #11
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    Re: Differential fluid additive. Do I need it?

    Thank you to everyone that helped me out. I just read the bottle of synthetic 75W 140 (towing heavy load) and it said it had some kind of additive for limited slip. No sure I have a limited slip, but if I do it must be protected. Thank you all, your awesome.

  12. #12
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    Re: Differential fluid additive. Do I need it?

    Mine says dana on the cover and is a 10 bolt

 

 

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