Differential Fluid Question

[belvedere]

....I bought 2 bottles yesterday which cost me over $40 with tax

What kind of gear oil?

 

[Powerslave]

Yeah, because here, even the good Synthetic like Royal Purple is only 8.99 a bottle on sale, that's all I paid for it a few years ago. Sure, it may be more now, but $40.00 is steep, I would not pay that; but, it can be as high as 17.99 for 85W140...

This place: http://www.rpmoutlet.com/royal.htm has it for $10.00 a quart, so you need to LOOK around first...

 

[tjkj2002]

Amen!

So what would a Master Certified Chrysler, Dodge, Jeep Technicianwavey.gif recommend for the KJ's differentials?

A Master ASE certified tech would use what the axle manufacture recommends,not who sold the axle but who actually made it.

You get better lubrication, less lubricant break down due to wear and heat, and generally speaking, components last longer if synthetic lube is used(this applies more to engines than diffs.)

Yep it applies more for engines and anything that uses pressure to keep lubricated.

The way diffs lubricate themselfs you want thick stuff that sticks to the gears,may take more power to turn but that is part of having correct lubrication for diffs,and that is another reason many manufactuers recommend synthetic gear oil since it has less paristic loss which equals better mpg's but actually less cooling ability in diffs.Synthetic fluids flow better so it does not stick to the gears as good as dino gear oil so not cooling the gears in extreme use(towing and offroad).This is more apparent in high pinion diffs since the gear oil needs to kinda not flow very well back into the pumpkin when it gets flung to the pinion bearings.

 

[Idaho08KK]

Synthetic fluids flow better so it does not stick to the gears as good as dino gear oil so not cooling the gears in extreme use(towing and offroad).

I have to disagree with you on that point. Every modern CDJ product that has a differential recommends synthetic fluid for heavy use applications. All of the Jeeps, except Compass & Patriot, all of the Dodge Rams recommend this.
Dodge Ram 2500 & 3500, which are used to tow large loads, use a 75w90 synthetic exclusively in the American Axles that they are equipped with. Use of any other lubricant will cause damage.
All of the Jeep products that are used to tow with recommend 75w140.

Now why would such companies as Dana, American Axle, and Chrysler recommend a synthetic lubricant for heavy use applications if it was indeed inferior?

 

[tjkj2002]

I have to disagree with you on that point. Every modern CDJ product that has a differential recommends synthetic fluid for heavy use applications. All of the Jeeps, except Compass & Patriot, all of the Dodge Rams recommend this.
Dodge Ram 2500 & 3500, which are used to tow large loads, use a 75w90 synthetic exclusively in the American Axles that they are equipped with. Use of any other lubricant will cause damage.
All of the Jeep products that are used to tow with recommend 75w140.

Now why would such companies as Dana, American Axle, and Chrysler recommend a synthetic lubricant for heavy use applications if it was indeed inferior?

Pressure from the government for higher mpg #'s,reason why most new vehicles are speced for 5w-20 engine oil.You will also notice a maintenance schedule that requires diff fluid changes more often when synthetic is recommended,the biggest reason again is higher mpg's for CARB.

 

[BjBnet]

What kind of gear oil?

Quaker synthetic...that's all I could find.
Got some for the rear today, only putting in the 90 and it's semi-synthetic. I tow my boat but not that much so I should be fine. I expect it'll be good for the winter as well.
I think I might even clean up my cover and paint it or something....we'll see.

 

[brucebotti]

I have to say that synthetic lubricants are superior to non synthetic. You get better lubrication, less lubricant break down due to wear and heat, and generally speaking, components last longer if synthetic lube is used(this applies more to engines than diffs.)
IMO, it is a safe bet to use whatever the manufacturer recommends. They either design it, test it, and build it, or they provide specifications to a 3rd party and have them manufacture the parts.
I would have to trust what a manufacturer says about their own products than what an aftermarket company had to say about them.

I agree! I'll purchase the synthetic and give the five quarts of dino that I have on the shelf to my son for his '95 Suburban.
Bruce

 

[belvedere]

I would like to see some actual evidence, in writing, of syn gear lubes being inferior. I'm thinking along the lines of an ASE paper; in other words, something with some scientific testing behind it, rather than some guy's opinion.

 

[RageOfFury]

Found an interesting post in another forum pertaining to Dino vs Syn...more like Amsoil vs Currie

Had a great conversation today with the Amsoil drivetrain fluid product manager. Strangely enough they have been recently approached by "A Company", (that has been discussed in depth in this thread for their dislike of synthetics), about private labeling two current Amsoil gear lubes for use with their off road & performance rear ends. Another air operated locker company is also in the final stages of naming a new Factory Fill for their products.

Also brought up was the fact that the owner of the company who doesn't prefer synthetics in their products, is an Amsoil dealer himself, and runs it exclusively in his own & his son's race vehicles. The Amsoil person who told me this had first hand knowledge of this. He read through this thread today & had some great laughs.

He showed me several test results measuring fluid, case & bearing temps in rear ends, proving to me with out a doubt that Amsoil synthetics are superior in heat reduction. The thought process on the molecular size not picking up heat from the metal is "nonsense". Amsoil's molecular uniformity is what makes it superior. The test results, that Currie & Auburn are basing their research on is nearly two decades old and used a synthetic oil at that time that was not the optimum product at that time, let alone now. Oil technology advances nearly every day. He suggested that any company still advising customers to stay away from synthetics needs to update their research.

If a company was sure that Synthetics were causing them problems, they wouldn't be seeking a private label for an Amsoil product. Now I have no proof to back up the private label claims, but also don't believe that would be made up. I have seen proof of other major companies looking for private label motorcycle & race oils. Mr. Amatuzio is very proud to put his own name on his products & doesn't believe that any of his products should have anything other than his name on them. That I know for a fact.

Hope this will ease the mind of a few of you wanting to run synthetics.

http://www.jeepforum.com/forum/showpost.php?p=7261820&postcount=127

 

[tjkj2002]

Found an interesting post in another forum pertaining to Dino vs Syn...more like Amsoil vs Currie



http://www.jeepforum.com/forum/showpost.php?p=7261820&postcount=127

Currie does have a recommended gear lube,they even have it labeled for them but it is more commonally known as Torco and no it is not synthetic.

 

[Powerslave]

The "Sticking" to metal parts of Dino -vs- Synthetic, there is no real difference. The thicker the oil, the more it sticks to the parts. Synthetic has all the properties Dino oil has, with the exception of added friction modifiers.

Limited slip differentials, you have a spring pack that pushes the side gears against the clutches, which are attached to the cage. All this is lubed by the gear oil, and just like in Motorcycle WET clutches, synthetic oil is NOT good this this type of Differential or CLUTCH system. The friction modifiers cause more slip before the clutches grab, thus a little more heat, and more wear.

The brochures for the liberty say they are OPEN DIFF front and rear, so, Synthetic is just fine. I have read other specs they are LSDs as well, so what actually are they?

 

[HoosierJeeper]

The brochures for the liberty say they are OPEN DIFF front and rear, so, Synthetic is just fine. I have read other specs they are LSDs as well, so what actually are they?

The off road package included a Trac Lock Limited Slip rear end...but the front was always an open.

 

[Powerslave]

Ok, so open Diffs are just fine for Synthetic oils. You may want to get more data on using them in the LSD diffs, as they are like a WET clutch set-up. The TracLok uses two sets of multiple disc clutches. They say to use "Special" Positive traction differential fluid, as specified by the MFR.

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#11 Shows the clutch plates.

TrackLok was for 02-05 models, what did they use for 06-07?

 

[tjkj2002]

TrackLok was for 02-05 models, what did they use for 06-07?

ESP(the devil)

Detroit also recommends dino oil if there lockers are used,that's for there locker and the DTT,both do not use any type of clutches.

 

[RageOfFury]

Well if synthetic isn't good for LSD, why does Chrysler recommend synthetic (75W-90 or 75W-140) then?

I notice they(Chrysler) recommend dino oil in the front but synthetic in the rear...again why?

I've found a whole lot of threads on this dino vs syn in diffs issue. All but 2-3 posts say to use what Chrysler recommends. I have to agree, my dad's 00 Durango has been on 75W-140 syn on both diffs since 40 000 KMs. He's now at 215 000 KMs with 0 issues. He's got the optional LSD in the rear as well.

When saying that x or x oil is bad, back it up with concrete proof, not hearsay.

 

[tjkj2002]

Well if synthetic isn't good for LSD, why does Chrysler recommend synthetic (75W-90 or 75W-140) then?

I notice they(Chrysler) recommends dino oil in the front but synthetic in the back...again why?

Heat issue,the front diff holds about 1qt less fluid and get's very little cooling air like the rear diff get's alot in comparison.It's not from the rear diff is always turning since the front "hubs" are always locked in the front so the front diff is always turning also,plus Chrysler did not make the front diff,Dana/Spicer did per Chrysler's spec's.

As far as LSD you must add a friction modifier that basically makes the gear oil less slippery so it can operate without chatter.

 

[RageOfFury]

I don't even own a Liberty yet, but this issue is making my head spin. One says to use oil X, another says no no use oil Z.screwy.gif

You know what...screw this(banghead). When I get my KJ, I'm just gonna follow what the owner's manual says. That's what my dad has been doing with is 2000 Durango and 0 issues so far (215 000KMs) pertaining to diffs, tcase, ******, engine. Did the same with his 88 XJ and 12y/302 000KMs later again 0 issues with the powertrain.

I guess if your an enthusiast, an extreme off-roader, than sure you can go off the map with your fluids. But for someone that drives around town and heads to the cottage every weekend, then following the owner's manual recommendations is more than enough.

/thread

 

[BjBnet]

You know what...screw this(banghead). When I get my KJ, I'm just gonna follow what the owner's manual says. That's what my dad has been doing with is 2000 Durango and 0 issues so far (215 000KMs) pertaining to diffs, tcase, ******, engine. Did the same with his 88 XJ and 12y/302 000KMs later again 0 issues with the powertrain.

I guess if your an enthusiast, an extreme off-roader, than sure you can go off the map with your fluids. But for someone that drives around town and heads to the cottage every weekend, then following the owner's manual recommendations is more than enough.

/thread

exactly. When you find a KJ let's all get together and have a lifting party nana.gif

 

[Powerslave]

As far as LSD you must add a friction modifier that basically makes the gear oil less slippery so it can operate without chatter.

That is why Syn is not really recommended in a LSD application, as they have friction modifiers that make it MORE "slippery." I use Synthetic ALL the time anyway, and have not had any problems with anything. I even use it in my WET CLUTCH motor cycle (20W50), so we'll "see" if the clutch wears prematurely as compared to how long they're supposed to last.

Since locking diffs have the same parts as an open differential, but adds an electric, pneumatic or hydraulic mechanism to lock the two output pinions together, Synthetic is ok.

Now, the Torsen differential, that's strictly a mechanical device; it has no electronics, clutches OR viscous fluids. Too bad we can't use them like a regular diff app. The Hummers use them. Though they are widely used used for high performance AWD autos, similar to viscous coupling...

I am a strict SYNTHETIC user, that's all I use. My avenger's motor only saw Syn, and at ran the same with 0 miles as it did with 150K+ miles on it. ATF+4 is synthetic transmission fluid ANYWAY, so that's covered. The only oil leak my Avenger saw, was the leaking from the OIL cap, it did that since day one. There is a rocker arm RIGHT UNDER the oil cap, and of course, an oil hole in it... If you take the oil cap off (710 Cap for blondes), while the car is running, oil will shoot straight out... V6 model of course... The oil hole just HAD to be on that side of the rocker...

Also, I don't know what the COOLING deals are, but synthetic can take more heat than Dino oils. They do not lose viscosity like regular oil either, so anything that runs hotter, I am using Synthetic anyway.

I will stick with what has been working for me for over 15 years... I save money by using Syn, so you don't have to change it ever 6K miles. I do it every 18K with Syn, and just change the filter at 6/7K. It is designed to last 25K miles in engine apps, and theoretically, CAN run it for 100K miles under normal conditions...

 

[jnaut]

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This is damn exciting stuff!