I have a 2006 liberty crd. I know the manual calls for lighter weight fluid, but would it cause a problem if I put 75W140 in both front and rear differential? Thanks.

The best protection for your diffs is to use non-synthetic gear oil.

Towing and offroad frequently = 85w-140 front and rear.

Towing and offroad in-frequently = 80w-90 front and 85w-140 rear.

None of the above = 80w-90 front and rear.

non synthetic? why ? synthetic handles heat much better than dino gear oils. Faster lubrication when gears are cold , better handling of extreme heat when rig is driven hard. You'd be nuts to not run synthetic.

???????

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Got Sheep?

2005 Jeep Liberty CRD 271'000+ KM's, ORM, Muffler Delete, MOROSO oil/air separator unit, 1000 CA battery, ARB Bull bumper, OME coils/shocks 2" lift. Custom BushRoo roof rack & Bush Joey hitch rack. Mobil1-301 oil filter & Mobil 1 DELVAC ESP 0W40 Full Synthetic oil, custom rear hatch cargo rack. RACOR 245 filterhead

For your engine and trans but not the diffs and synthetic is terrible at heat transfer in a splash oiled system.

You don't want the oil the flow faster in your diff,you want it to be thick and stay in place.Two of the top offroad aftermarket diff builders specifically ban the use of synthetic gear oil and those diffs are typically turning 35" to 44" tires in more extreme conditions your KJ will ever see.

Well, guess I have some diff maintenance to do then....been running 75w140 red line synthetic ester diff oil for the last 145,000 km's

On road, sustained Hwy driving, off-road

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Got Sheep?

2005 Jeep Liberty CRD 271'000+ KM's, ORM, Muffler Delete, MOROSO oil/air separator unit, 1000 CA battery, ARB Bull bumper, OME coils/shocks 2" lift. Custom BushRoo roof rack & Bush Joey hitch rack. Mobil1-301 oil filter & Mobil 1 DELVAC ESP 0W40 Full Synthetic oil, custom rear hatch cargo rack. RACOR 245 filterhead

Different applications may benefit from a mineral base gear lube. I for one will stick with synthetic. I use Mobile 1 75W-90 synthetic front and rear and I don't tow.

https://www.bobistheoilguy.com/forums/u ... er=2855799

You can use what ever you want but a few points...................

-Just because the diff housing is cooler to the touch does not mean the internals are cooler,this is true for synthetic gear oils were the heat is trapped in the gears and bearings.Conventional gear oil will transfer the heat to the housing that is exposed to air to cool it.

-Conventional gear oil sticks to gears/bearings,useful for offroad when in off-camber maneuvers.Synthetic gear oil will flow to freely to the other side leaving bearings with little to no lubrication.

-Synthetic gear oil has been put into vehicles from the factory for 1 purpose,better mpg's and most have a significant shorter OCI's for diffs.

-If you tow or offroad you naturally want to(and should be) change gear oil more frequently and let's face it at an average cost of $18 per qt for synthetic it get's expensive compared to $5 per qt for conventional gear oil.

-From personal and professional experience I have stopped many diff seal leaks by simply switching the gear oil to conventional oil.

I agree with tj, and I'd recommend especially the Lucas mineral oil 85w140.



I also use it in the rear Diff in the crd. It's also recommended by most custom axle builders for offroad use. On road use with very limited offroad, you'd probably be better with synthetic, you get better mileage and you won't hurt any bearings if you tilt the jeep sideways for few times few seconds while you go through a ditch. But when you do this multiple times, the non synthetic oil is better since it binds more on the axle components insuring a superior lubrication. It's also thicker and many people use it to stop seal leaks.

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2005 kj CRD, samco, suncoast tc, provent, Kennedy lift pump, GDE ECO full torque, 2nd gen filter head, 245/70/16 a/t tires, mopar light bar, fumoto oil valve, OEM Skid Plates, ARB Front bumper and HD OME, tru cool LPD47391 40k GVW tranny cooler (stock cooler delete), FF Dynamics e-fan and shroud, rocker arms replaced, HDS2 190F thermostat.

Swepco 212, 80w-140 with moly is the ultimate hypoid gear oil for longevity. It is a non-synthetic, multi-weight and quite expensive. TJ covered the reasons.

DOC

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2005 KJ CRD Ltd Detroit TrueTrac Bilsteins G2 GDE "HOT" ECU GDE TCM "Tow Tune" "euro" TC SEGR Weeks Elbow New HG at 130K ARPs Clean CAT aFe Filter Magnaflow Exhaust EHM Cumminos In-Tank Lift Pump Hayden Fan Clutch Nylon Fan VH Enabled with GDE lower shutoff point Recalibrated Temp Gauge Tekonsha Prodigy Sears P-1 ZDDP

Yeah, I added thin stuff for mileage and my rear pinion started leaking. I put back in heavy mineral and it quit leaking

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05 CRD: H.D.S2 stat,WW Ironrock trilink&LCA's, OX rear,ARB front, 4.10's, ARB bumper, Suncoast,OME 3.5, JBA UCA,rock rails, Moabs&265/75 Duratracs, GDE tunes ,FFD fan,ARP's, 2 micron fuel, new valves,sasquatch battery tray & grid heater, tensioner relocated
Mech fan, VH & AC delete

I have been using synthetics for years but a while ago I was going to go back to conventional gear oil based on TJ's thoughts. I ended up staying with the synthetic gear oil but added Lucas oil Stabilizer to increase the cling of the synthetic gear oil.

I like the sound of that. I would really like to gain 1mpg but still have the needed protection. But, I did tow extremely heavy loads over large grades for a couple of years and my diff survived, maybe I'm lucky? I'm throwing new gears in with a locker just to be safe, plus the gear pattern is much easier to read with new gears

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05 CRD: H.D.S2 stat,WW Ironrock trilink&LCA's, OX rear,ARB front, 4.10's, ARB bumper, Suncoast,OME 3.5, JBA UCA,rock rails, Moabs&265/75 Duratracs, GDE tunes ,FFD fan,ARP's, 2 micron fuel, new valves,sasquatch battery tray & grid heater, tensioner relocated
Mech fan, VH & AC delete