LOST JEEPS
http://www.lostjeeps.com/forum/phpBB3/

Differential fluid question
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=54357		 Page 1 of 4
Author:  JDaPP [ Sun Jul 18, 2010 11:08 pm ]
Post subject:  Differential fluid question
I know this is a silly question but this is the first time I am changing the differential fluids and I want to make sure I don't screw it up (have used the search, I just want to make sure I have it all straight).
For the rear I need 4.3 pints of 75w-140 ( I do tow from time to time) and additive for the LSD. For the front I need 2.6 pints, of 80w-90? Can I use 75w-90 or should I use 75w-140 or does it really matter? Also I purchased a gasket already from Pep boys, I know it is a cheapo but I would assume it is okay?
Author:  Cowpie1 [ Mon Jul 19, 2010 2:40 pm ]
Post subject:  Re: Differential fluid question
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.
Author:  KJ 119 [ Mon Jul 19, 2010 4:06 pm ]
Post subject:  Re: Differential fluid question
I put additive in the rear of my 06.
Didn't know they don't need it.Is this bad to add when not needed?
Author:  bugnout [ Mon Jul 19, 2010 4:34 pm ]
Post subject:  Re: Differential fluid question
If you have LSD, you should put the additive in.

I use 75-140 syn front and back.
Author:  dgeist [ Mon Jul 19, 2010 4:52 pm ]
Post subject:  Re: Differential fluid question
bugnout wrote:
If you have LSD, you should put the additive in.

I use 75-140 syn front and back.


Yes, but with all the weight you carry, it's like towing all the time :wink:

I use 75W-90 front and 75W-110 in the rear for the few times I actually do tow, both full-syn, oh, and the lubelocker; You'll thank yourself at the first change after buying one.

KJ 119 wrote:
I put additive in the rear of my 06.
Didn't know they don't need it.Is this bad to add when not needed?


Bub, I've seen it reported that it's detrimental, but as nothing it designed to slip in a normal diff, I'm not sure how... Perhaps they mean the small hole it burns in your wallet. It definitely doesn't do anything good for ya.

Dan
Author:  RAF 3829 [ Mon Jul 19, 2010 6:45 pm ]
Post subject:  Re: Differential fluid question
I use 75w-90 front and rear.
Author:  racertracer [ Mon Jul 19, 2010 7:04 pm ]
Post subject:  Re: Differential fluid question
Here is some necessary information on "WIKI BOOKS" regarding our Jeep Liberty and fluids.


http://en.wikibooks.org/wiki/Jeep_Liber ... _Intervals
Author:  LibertyCRD [ Mon Jul 19, 2010 8:31 pm ]
Post subject:  Re: Differential fluid question
On the CRD the owners manual specifically calls for 75W140 synthetic in the rear. I wouldn't use anything else.

In the front I used 85W90 syn.
Author:  Big Montana [ Mon Jul 19, 2010 8:42 pm ]
Post subject:  Re: Differential fluid question
Ive always wondered if my 05 has a LSD. How would I know. It doesn't say on the invoice. Shouldn't EVERY CRD be the same?
Author:  yakers [ Mon Jul 19, 2010 8:45 pm ]
Post subject:  Re: Differential fluid question
I saw a posting on this site in the last few weeks that indicated that synthetic diff fluid does *not* last longer than dyno stuff, specifically it does not allow extended longer drain periods. Seems strange to me, any data elements omewhere that support this? Most vehicles I have owned had it changed maybe @ 100K miles, once in its life. So it seems strange to have the frequency called out in the CRD manual. But I do tow and change it per the schedule w/75/140 in the rear. Replaced the rear diff cover with a Ruff Stuff one that has a drain plug.
Author:  LibertyCRD [ Mon Jul 19, 2010 9:02 pm ]
Post subject:  Re: Differential fluid question
Big Montana wrote:
Ive always wondered if my 05 has a LSD. How would I know. It doesn't say on the invoice. Shouldn't EVERY CRD be the same?


No, my previous '05 did not have the "Trak-Loc" rear axle. This '05 I'm driving now does have the Trak-Loc, and according to the window sticker (still in the owner's manual folded away) it was a $300 option. So I had to use the LSD additive this time.
Author:  Big Montana [ Mon Jul 19, 2010 9:19 pm ]
Post subject:  Re: Differential fluid question
Well I bought mine new and I don't recall any indication that I have it. I would love to figure out what rear axle I have. Would the axle always be the same? I think it would be good for CRD owners to figure out whether or not they have the LSD if the additive is harmful to the non-LSD Difs.
Author:  tjkj2002 [ Mon Jul 19, 2010 9:24 pm ]
Post subject:  Re: Differential fluid question
yakers wrote:
I saw a posting on this site in the last few weeks that indicated that synthetic diff fluid does *not* last longer than dyno stuff, specifically it does not allow extended longer drain periods. Seems strange to me, any data elements omewhere that support this? Most vehicles I have owned had it changed maybe @ 100K miles, once in its life. So it seems strange to have the frequency called out in the CRD manual. But I do tow and change it per the schedule w/75/140 in the rear. Replaced the rear diff cover with a Ruff Stuff one that has a drain plug.

That is right synthetic gear oil does not last longer in diffs.This is only for gear oil.The reason is synthetic gear oil does not transfer heat like dino gear oil and has been known to burn up pinion bearings if not changed at 12k-15k intervals.


Many high end aftermarket axle builders(Hi9 and Currie) strictly forbid synthetic gear oils in there diffs unless you like changing pinion bearings every 200 miles or so.
Author:  kdlewis1975 [ Mon Jul 19, 2010 9:42 pm ]
Post subject:  Re: Differential fluid question
yakers wrote:
I saw a posting on this site in the last few weeks that indicated that synthetic diff fluid does *not* last longer than dyno stuff, specifically it does not allow extended longer drain periods. Seems strange to me, any data elements omewhere that support this? Most vehicles I have owned had it changed maybe @ 100K miles, once in its life. So it seems strange to have the frequency called out in the CRD manual. But I do tow and change it per the schedule w/75/140 in the rear. Replaced the rear diff cover with a Ruff Stuff one that has a drain plug.


In the case of synthetic fluids, it isn't always about longer intervals, though this a nice attribute when appropriate. Because synthetics are a bit more designed at the molecular level, one has a bit better over the viscosity characteristics. In general, the viscosity versus temperature curve is flatter...things still get thinner as the temperature rises, but the change is not as great. In general, the flow at cold temperatures is better than that of a conventional oil. So, disregarding potential differences in lubricity, if you live somewhere that is predominantly warm, then use whichever.

I'm pretty sure the owners manual for my 06 states that either the 75w90 or Xw140 stuff (which I use) is fine for the rear diff. It just recommends the thicker stuff for heavy duty service. It would be to our advantage to use the thinner stuff in the winter for those of us that experience the cold.

Because of the traction control, all 06s are OEM open diffs, so no need for the additive. While I don't think it's a good thing to use, it should be all that rough on it since the trac-lock diffs share some same parts and those aren't flying apart any faster...?
Author:  kdlewis1975 [ Mon Jul 19, 2010 9:55 pm ]
Post subject:  Re: Differential fluid question
tjkj2002 wrote:
yakers wrote:
Many high end aftermarket axle builders(Hi9 and Currie) strictly forbid synthetic gear oils in there diffs unless you like changing pinion bearings every 200 miles or so.


I'm a professional chemist. The difference in heat capacity and heat transfer of conventional vs. synthetic base oil will be negligible. It may come down to additives, but with these being a minor component, they should only play a small role. In the absence of physical measurements for the above data, this is just as hard to believe as the last time it was posted.

If someone is blowing a pinion bearing after just 200 miles using synthic gear lube, it's probably because they didn't fill the diff in the first place.

In dieties we trust, all others bring data.
Author:  Drewd [ Mon Jul 19, 2010 10:10 pm ]
Post subject:  Re: Differential fluid question
What is this lubelocker gasket and where can I get one?
Author:  tjkj2002 [ Mon Jul 19, 2010 11:44 pm ]
Post subject:  Re: Differential fluid question
kdlewis1975 wrote:
tjkj2002 wrote:
yakers wrote:
Many high end aftermarket axle builders(Hi9 and Currie) strictly forbid synthetic gear oils in there diffs unless you like changing pinion bearings every 200 miles or so.


I'm a professional chemist. The difference in heat capacity and heat transfer of conventional vs. synthetic base oil will be negligible. It may come down to additives, but with these being a minor component, they should only play a small role. In the absence of physical measurements for the above data, this is just as hard to believe as the last time it was posted.

If someone is blowing a pinion bearing after just 200 miles using synthic gear lube, it's probably because they didn't fill the diff in the first place.

In dieties we trust, all others bring data.

Go and call Hi9 and Currie and ask there opinion on syn diff fluids,those guys make diffs and know there stuff.There is a huge difference between dino and syn gear lubes and dino wins in this category.
Author:  mackruss [ Wed Jul 21, 2010 7:34 am ]
Post subject:  Re: Differential fluid question
LibertyCRD wrote:
On the CRD the owners manual specifically calls for 75W140 synthetic in the rear. I wouldn't use anything else.

In the front I used 85W90 syn.


X2 and trust me i've gone through 2 diff replacements already, use synthetic and change more frequently than advised.
Author:  europachris [ Wed Jul 21, 2010 1:55 pm ]
Post subject:  Re: Differential fluid question
tjkj2002 wrote:
That is right synthetic gear oil does not last longer in diffs.This is only for gear oil.The reason is synthetic gear oil does not transfer heat like dino gear oil and has been known to burn up pinion bearings if not changed at 12k-15k intervals.


Many high end aftermarket axle builders(Hi9 and Currie) strictly forbid synthetic gear oils in there diffs unless you like changing pinion bearings every 200 miles or so.


I keep reading about this "myth" regarding heat transfer and synthetic oils and I don't buy it. Just like the myth about synthetic being too slippery for engine break-in even though several vehicles have factory fill synthetic oil in the engine rolling out the door. Engine break-in (primarily ring seating) is dependent upon HEAT and PRESSURE due to putting a LOAD on the engine. Pussyfooting around will glaze up the bores regardless of what oil you have.

If a diff is eating pinion bearings, it's due to poor design or poor parts, IMHO. Synthetic oils provide superior film strength and resist viscosity shear (provided that proper additive levels are in the oils). Not all synthetic oils are created equal, either. I'm not a member of the Amsoil fan club, I don't even use any of their products, but the gear oil "whitepaper" they did is informative, if nothing else: http://www.amsoil.com/lit/g2457.pdf. If the CRD rear end is eating itself, I can bet you that it's doubful the synthetic oil is causing it. It's a lot more likely that Chrysler sourced the cheapest Chinese bearings they could find and probably the gears are from China or India and cast out of rejected manhole covers.

I'm also guessing that Chrysler put fairly frequent diff oil changes in the "severe service" schedule to account for off-roading and the potential for water ingression. In my stint at a quick-lube during college, I changed out a LOT of diffs and saw plenty of gear oil that looked like black driveway tar (and smelled like it), badly foamed oils, and stuff that looked like the filling out of a Milky Way bar or greenish brown mayonnaise. :shock:

I'm not trying to start a pi$$ing contest, but I see a lot of misinformation and "urban legend" spewed forth regarding synthetic oils. Maybe someone put synthetic oil in his rear end on an 800 hp 200 mph race car and it burned up. Well, I can assure you that if the rear end didn't have a pump and oil cooler system, it was going to burn up regardless of what was in there.
Author:  NJCRD [ Wed Jul 21, 2010 4:14 pm ]
Post subject:  Re: Differential fluid question
This is what I have been running in mine.

http://www.redlineoil.com/product.aspx?pid=44&pcid=8

Real nice stuff.
Page 1 of 4 All times are UTC - 5 hours [ DST ]
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
http://www.phpbb.com/