Differential fluid question

Cowpie1 · **Posted:** Sun Aug 01, 2010 10:54 am

kdlewis1975 wrote:

tjkj2002 wrote:

Oh and forced lubrication is not the same as a "splash" lubricated system,2 totally different requirements for proper lubrication.

I've heard this before too. Some of the testing used is different too. However, I don't know the details. Can you explain? Do you have any references to journal or SAE papers? Will be peer reviewed and the least biased of the available sources. Spare us the testimonials and sales sheets from manufacturers.

I referred you earlier to the Technology and Maintenance Council. Go ahead and take your best shot with them on this. They recommend synthetics based on their testing. Their testing is done in real world conditions involving real equipment doing real work. Most of their committee members are seasoned mechanics with several decades of experience. Since they are the defacto standard for OEM's and fleet owners, they have to be careful in what they recommend. They do not issue recommended practices overnight. They amass several million miles of testing before reaching conclusions.

CATCRD · **Posted:** Sun Aug 01, 2010 12:40 pm

Neal wrote:

The 05 manual states to use 75-140 synthetic for front and 75-90 for rear(for towing 75-140 synthetic.
I use 75-140 synthetic front and 75-140 dino rear.
Seems the specs change from year to year :roll:

Are you sure you don't have that backwards? My 2005 manual states the same thing stoutdog posted:

Axle Differential (Front):
Mopar Gear & Axle Lubricant (SAE 80W-90) or equivalent.

Axle Differential (Rear):
Mopar Synthetic Gear Lubricant (SAE 75W-90) or equivalent. For trailer towing, the lubricant should be replaced with Mopar Synthetic Gear & Axle Lubricant (SAE 75W-140) or equivalent. Models equipped with Trac-LokTM require a limited-slip additive.

SPN-87 · **Joined:** Tue Mar 09, 2010 3:09 pm **Posts:** 53

CATCRD +1

Jeep Liberty (Cherokee) KJ
Service manual

page 0-3 Lubrication & maintenance

AXLE
NOTE: DaimlerChrysler recommends using MoparT
lubricants or lubricants of equal quality.
FRONT AXLE
² 186FIA (Model 30) - Mopart Lubricant 80W-90
REAR AXLE
² 8 1/4 - Mopart Gear Lubricant 75W-90 (Trailer
Towing - Mopart Synthentic Gear Lubricant 75W-140
NOTE: Trac-lokT equipped axles require 118 ml (4
ounces) of Limited Slip Additive be added to the
lubricant.

Neal · **Posted:** Sun Aug 01, 2010 4:29 pm

CATCRD wrote:

Neal wrote:

The 05 manual states to use 75-140 synthetic for front and 75-90 for rear(for towing 75-140 synthetic.
I use 75-140 synthetic front and 75-140 dino rear.
Seems the specs change from year to year :roll:

Are you sure you don't have that backwards? My 2005 manual states the same thing stoutdog posted:

Axle Differential (Front):
Mopar Gear & Axle Lubricant (SAE 80W-90) or equivalent.

Axle Differential (Rear):
Mopar Synthetic Gear Lubricant (SAE 75W-90) or equivalent. For trailer towing, the lubricant should be replaced with Mopar Synthetic Gear & Axle Lubricant (SAE 75W-140) or equivalent. Models equipped with Trac-LokTM require a limited-slip additive.

Not all manuals are created equally, I just looked at an 05 manual online and it is differant than my manual. It agrees with yours.
Don't think it is that big a deal.

racertracer · **Posted:** Sun Aug 01, 2010 4:56 pm

kiasoul · **Joined:** Tue Aug 03, 2010 12:15 pm **Posts:** 30

Guy with orange jeep has a point. I to belive dino oils for axles maybe a better oil. I replaced my BMW with redline and found axle didnt really like it. Switched back to dino. At napa they have gear cutout, watching the oils climb up teeth syn seemed really thin while dino climbed higher and offered more shock protection. Could be chrysler found thicker syn works good offers more shock protection? I will use what chrysler recommends. Anyone using rotella white bottle 5w40? We could save a but load in cash and change it every 4k miles. Royal purple say's no LSD additive is needed when using there product? My nissan truck has this in it with LSD

nursecosmo · **Posted:** Thu Aug 05, 2010 1:30 am

kiasoul wrote:

Guy with orange jeep has a point. I to belive dino oils for axles maybe a better oil. I replaced my BMW with redline and found axle didnt really like it. Switched back to dino. At napa they have gear cutout, watching the oils climb up teeth syn seemed really thin while dino climbed higher and offered more shock protection. Could be chrysler found thicker syn works good offers more shock protection? I will use what chrysler recommends. Anyone using rotella white bottle 5w40? We could save a but load in cash and change it every 4k miles. Royal purple say's no LSD additive is needed when using there product? My nissan truck has this in it with LSD

If the cutout you saw at Napa is the same one as at all other Napas in the nation, it does not compare synthetic vs dino. It shows oil with and without lucas additive. Dino lube of X viscosity is exactly the same viscosity as synthetic of the same weight at API temperature parameters. Where synthetic really shines, is above and below the tested temps. It stays thicker at higher temps and thinner at lower temps. Contrary to what some have stated, Synthetic is accepted by industry, and academia as well as NASA, as having greater shear strength than dino.

europachris · **Posted:** Tue Jul 12, 2011 9:04 am

Digging up an old (and a bit sore) topic here, but I read in a recent article of Sport Aviation magazine, published by the Experimental Aircraft Association, that a company that builds gearbox reduction units to convert auto engines for aircraft use tried synthetic lubes and consistently had overheating problems with the lube oil. They switched back to dino oil and the problem went away. I found it very interesting and gives another data point regarding synthetic gear lubes not necessarily being all they are cracked up to be. This particular gear drive unit has a separate pump, cooler, and filter system as well as temperature monitoring and chip detection. It is also a straight spur gear drive.

Joe Romas · **Posted:** Thu Jul 14, 2011 7:08 am

kiasoul wrote:

Anyone using rotella white bottle 5w40? We could save a but load in cash and change it every 4k miles.

Most of the White Bottle Rotella I've seen is 15w40 but I have seen stright 30W too

SLS · **Posted:** Thu Jul 14, 2011 8:40 pm

Cowpie1 wrote:

I would recommend a synthetic (brand your choice) 75w90 up front with 75w140 in the rear. The gasket you bought should be fine. In the future I would recommend getting the LubeLocker rear gasket. I have reused one of those several times. I have a 2006 and no additive is needed in the rear, not sure about the 2005.
You could use 75w140 up front I suppose, but every place I checked, 75w90 is always the recommended weight. If you are looking for getting the best fuel mileage, the 75w90 would be the better choice.

I'm with you on the synthetic
I changed all the drive train fluids to AMSOIL.
Here are some specs that may help:
SEVERE GEAR 75W-90 Synthetic EP Lubricant (SVGQT)
2.6 pints in the front: 1.3 qts
4.3 pints in the rear: 2.15 qts
3.45 qts total
Automatic Transmission, 545RFE Initial Fill..........5 quarts (8) Case
Synthetic Universal Automatic Transmission Fluid (ATFQT)

Transfer Case,......AP4 Transfer Case, NV241..........4.3 pints 2.15qts
Synthetic Universal Automatic Transmission Fluid (ATFQT)

Transmission filter WIX 58843 Auto Tran Filter
There are 2 transmission filters on this vehicle.
Chry filter:
Internal (part #5013470AC) - $33.80, (prices when I replaced them)
External (part #5179267AC) $18.70
I saw an increase in MPG. But that could be just me or cleaner fluid.....

Ajamant · **Posted:** Thu Sep 01, 2011 4:15 pm

It's very clear a lot of you know far more about this topic than I. I do run fully synthetic everything in all my vehicles, that includes a lifted TJ.

Im sure many of you are familiar with Stu Olsons website, primarily dedicated to wranglers. The guy knows his stuff so I'll quote from his site:

"I use Mobil 1 75W-90 gear lube in both the front and rear differentials (D30 and D44 respectively). This is a GL-5 rated synthetic gear lube. Since I don't have problems with fluid contamination (such as getting water in the differential), I only change the fluid annually. The couple of extra dollars it costs for Mobil 1 is not an issue and the hard work that the ring and pinion gears see warrants a good lube, in my opinion. Some folks who live in wet areas change their diff fluids multiple times per year (water gets into the housing) and so opt to use regular dino oil versus synthetic. "

Differential fluid question

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