Changing diff fluid, do I need LSD additive?
JK Enthusiast
Joined: Jun 2009
Posts: 483
Likes: 0
From: N.E. B.F.E. Indiana (Rome City)
I have used Valvoline products for ever! never have I had any issues with any car or truck I've owned!!!
With my JK, I use only their full synthetic oils and gear lubes, I have the Rubi, with the stock lockers, I DO NOT have to add the additive for this...
The gear lube the dealers use is NOT synthetic lube, so they have to use the adds...
I run the 75/90 in the front diff, and 75/140 in the rear and am very comfortable with my choice!!.....
I am not a cirtified mechanic, but I have been wrenching for more than 30 years on cars, trucks, bikes, sleds etc... so if I have been doing something wrong, it has'nt bit me in the ass yet!!!
Just my .02$!!!!!
With my JK, I use only their full synthetic oils and gear lubes, I have the Rubi, with the stock lockers, I DO NOT have to add the additive for this...
The gear lube the dealers use is NOT synthetic lube, so they have to use the adds...
I run the 75/90 in the front diff, and 75/140 in the rear and am very comfortable with my choice!!.....
I am not a cirtified mechanic, but I have been wrenching for more than 30 years on cars, trucks, bikes, sleds etc... so if I have been doing something wrong, it has'nt bit me in the ass yet!!!
Just my .02$!!!!!
JK Jedi
Joined: Feb 2008
Posts: 7,215
Likes: 10
From: Georgia
Gotta do the homework! I don't feel like forking out the coin for new gears, tranny, T-Case etc for using something I shouldnt have so I might as well do it right the first time. I bought some Mobil Super ATF+4 for the T-case, its not synthetic and says nothing on the bottle about T-Case's however the product sheet from Mobil's website states "Mobil Super ATF+4® can be used in other services that specify an MS-7176E® type fluid, including certain manual transmissions, transfer cases and power steering units". Jeep manual just says Mopar ATF+4 or equivalent, I should be good to go?
JK Newbie
Joined: Sep 2006
Posts: 87
Likes: 0
From: Cleveland, OH
why does the our JK call for 75/90 in the front diff, and 75/140 in the rear diff?
Is the diff fluid a gear lube and should be different then transmission fluid?
Is the diff fluid a gear lube and should be different then transmission fluid?
Last edited by pmergler; Oct 19, 2009 at 05:17 PM.
Thread Starter
JK Freak
Joined: Dec 2008
Posts: 796
Likes: 0
From: Halifax, Nova Scotia
It calls for 75/140 in the rear if you're using your JK for towing, if you arent then use 75/90. Diff fluid AKA gear lube/oil should never be used in your tranny unless it says to do so in your owners manual.
JK Newbie
Joined: Sep 2006
Posts: 87
Likes: 0
From: Cleveland, OH
Doing some research on sync diff fluids. Here is what I found:
Mobil1 sync.: Both the 75W140 and 75W90 ($8.99/qt) Mobil1 sight specifies that their product does have LSD additives (thanks mudmagnet63)
https://www.mobiloil.com/USA-English..._75W-90LS.aspx
https://www.mobiloil.com/USA-English...75W-140LS.aspx
Amsoil: They only have 75W90 in their long life line (not 75W140). The 75W90 long life product states it is compatible with most limited slips. (but it never specifically states it has additives. It just states if shutter does occur then add additive). http://www.amsoil.com/storefront/fgr.aspx Has any one called to confirm if this Amsoil does or doesn't have additives?. They do offer a 75W140 ($15.15/qt) in their heavy gear line (they also have a 75W90 in this line). Can anyone confirm if the JK needs the 75W90 heavy gear ($12.75/qt) vs. their long life ($10.75)? http://www.amsoil.com/storefront/svo.aspx
Quaker State: they have a 75W90 and 80W140 FCI Sync. Their product documentation states it has "additives" but doesn't address if it is applicable for LSD application without additional additives. http://www.pennzoil-quakerstate.com/...nLubricant.pdf
Mobil1 sync.: Both the 75W140 and 75W90 ($8.99/qt) Mobil1 sight specifies that their product does have LSD additives (thanks mudmagnet63)
https://www.mobiloil.com/USA-English..._75W-90LS.aspx
https://www.mobiloil.com/USA-English...75W-140LS.aspx
Amsoil: They only have 75W90 in their long life line (not 75W140). The 75W90 long life product states it is compatible with most limited slips. (but it never specifically states it has additives. It just states if shutter does occur then add additive). http://www.amsoil.com/storefront/fgr.aspx Has any one called to confirm if this Amsoil does or doesn't have additives?. They do offer a 75W140 ($15.15/qt) in their heavy gear line (they also have a 75W90 in this line). Can anyone confirm if the JK needs the 75W90 heavy gear ($12.75/qt) vs. their long life ($10.75)? http://www.amsoil.com/storefront/svo.aspx
Quaker State: they have a 75W90 and 80W140 FCI Sync. Their product documentation states it has "additives" but doesn't address if it is applicable for LSD application without additional additives. http://www.pennzoil-quakerstate.com/...nLubricant.pdf
Last edited by pmergler; Oct 20, 2009 at 06:04 AM.
JK Newbie
Joined: Oct 2009
Posts: 32
Likes: 0
From: Rock & A Hard Place / OK
From the Mobile 1 web site
Mobil 1 Synthetic Gear Lube LS 75W-90 is a supreme performance, synthetic, multi-purpose, SAE 75W-90 automotive gear lubricant designed to meet the highest level of performance requirements of modern passenger vehicles in all types of operating conditions, including limited slip applications, as well as delivering outstanding power transfer performance.
Compared to conventional hypoid gear lubricants, Mobil 1 Synthetic Gear Lube LS 75W-90 performs exceptionally well over a wide range of temperatures. Mobil 1 Synthetic Gear Lube LS 75W-90 achieves this through a unique proprietary formulation that delivers optimized viscosity as a function of temperature properties together with the highest level of inherent formulation stability and protects against thermal and oxidative degradation, wear and corrosion, and viscosity loss associated with premature shearing. It also can be used in extended service and for aiding in fuel economy performance.
Mobil 1 Synthetic Gear Lube LS 75W-90 contains special friction modifiers designed for limited slip-type differentials. In most applications, the addition of special LS (limited slip) additives is not required. For axles requiring the highest level of limited-slip performance, OEM specific LS additives can be added to this fluid.
Mobil 1 Synthetic Gear Lube LS 75W-90 is a supreme performance, synthetic, multi-purpose, SAE 75W-90 automotive gear lubricant designed to meet the highest level of performance requirements of modern passenger vehicles in all types of operating conditions, including limited slip applications, as well as delivering outstanding power transfer performance.
Compared to conventional hypoid gear lubricants, Mobil 1 Synthetic Gear Lube LS 75W-90 performs exceptionally well over a wide range of temperatures. Mobil 1 Synthetic Gear Lube LS 75W-90 achieves this through a unique proprietary formulation that delivers optimized viscosity as a function of temperature properties together with the highest level of inherent formulation stability and protects against thermal and oxidative degradation, wear and corrosion, and viscosity loss associated with premature shearing. It also can be used in extended service and for aiding in fuel economy performance.
Mobil 1 Synthetic Gear Lube LS 75W-90 contains special friction modifiers designed for limited slip-type differentials. In most applications, the addition of special LS (limited slip) additives is not required. For axles requiring the highest level of limited-slip performance, OEM specific LS additives can be added to this fluid.
JK Newbie
Joined: Sep 2006
Posts: 87
Likes: 0
From: Cleveland, OH
oops...
Thanks, I mis-read that page. I read the just the part about additional additives can be added (but that was saying for extreme performance). That is what I get for just using page find rather than reading the whole thing. I will update my post.
Does anyone know a place to buy Mobil1 Gear LS 75W140? I can't find it via froogle.com except at one place on ebay for $24 a qt.
Thanks, I mis-read that page. I read the just the part about additional additives can be added (but that was saying for extreme performance). That is what I get for just using page find rather than reading the whole thing. I will update my post.
Does anyone know a place to buy Mobil1 Gear LS 75W140? I can't find it via froogle.com except at one place on ebay for $24 a qt.
Last edited by pmergler; Oct 20, 2009 at 06:14 AM.
JK Newbie
Joined: Oct 2009
Posts: 32
Likes: 0
From: Rock & A Hard Place / OK
I think I will add the modifiers in the mobil 1. If a jeep isn't used in Extreme conditions what is?
While we are on the subject do most of you use RTV silicone to seal the diff back up or go with a gasket and silicone? The last time I used RTV alone I had a small drip, on the following fluid change I used a gasket with a small amount of RTV and no leak
While we are on the subject do most of you use RTV silicone to seal the diff back up or go with a gasket and silicone? The last time I used RTV alone I had a small drip, on the following fluid change I used a gasket with a small amount of RTV and no leak