OK ..so I am getting ready to change diff fluids.

Depends on what year you have to as what is recommended.My '02 speced 80w-90 dino gear oil for the front.Though with my HP axles I will only use 85w-140 dino gear oil only,I don't like changing pinion bearings every 200miles.

x2 what tjkj said...

It really depends on your year/model...Right out of my 02 manual....

"Models equiped with trac-lock should use (75-140) with friction modifier"

or use (75-140) with towing applications

According to The StealerShip 75w140 is the only fluid that should ever be in the D30A, Especially if you wheel. 75w90 rear without towing package if you have a Trac-Loc use the additive. Towing Package or wheeling 75w140 same for the Trac-Loc use additive no way around it if you like your Trac-Loc. That's for my 2004

Red_KJ_666 said:

According to The StealerShip 75w140 is the only fluid that should ever be in the D30A, Especially if you wheel. 75w90 rear without towing package if you have a Trac-Loc use the additive. Towing Package or wheeling 75w140 same for the Trac-Loc use additive no way around it if you like your Trac-Loc. That's for my 2004

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There only referring to newer models,older KJ's say 80w-90 in the front diff.

Point being you what you want as long as you change it as per the maintenance schedule which is 12k-15k.

tjkj2002 said:

There only referring to newer models,older KJ's say 80w-90 in the front diff.

Point being you what you want as long as you change it as per the maintenance schedule which is 12k-15k.

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Yes Sir Mr. Masta Sir (bowdown) Every 15k since its been mine lol

tjkj2002 said:

There only referring to newer models,older KJ's say 80w-90 in the front diff.

Point being you what you want as long as you change it as per the maintenance schedule which is 12k-15k.

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How much older? I know my '04 manual specs 75w140 for the front, but what is the difference between my '04 and your '02, front axle-wise?

tjkj2002 said:

Man that is super,wish others would be the same as there vehicles would last longer with fewer problems and people would stop ******** all the time.Most think schedule maintenance is only a suggestion and they don't need to do it.Those 7/70,5/100,and lifetime powertrain warranty's have pretty strict rules to keep them as it leaves the scheduled maintenance totally up to the owner as to if they want to keep the warranty or lose it(without there knowledge).

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Even my lady knows to do regular maintenance. She has had her 04 saturn since new and now it has almost 100k miles and runs perfect. She always got the oil & filter, tires rotated, etc.. at the specified intervals or even earlier if she got a coupon for a free oil change from the saturn dealer (which is now gone). When I met her the tire place she got the tires from rotates her tires for free and told her new rear shocks and new rear brake pads (not even turning the drums) was gonna be right around $800. I did it in a few hours thanks to my local auto parts store turning drums in house for less than 1/4 of that. Maybe that is why she is marrying me

Thanks for the heads up on changing synthetic more often, I did not know that.

osufans said:

How much older? I know my '04 manual specs 75w140 for the front, but what is the difference between my '04 and your '02, front axle-wise?

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See....my front axle specs 80w-90 and mine is an '04 build date 5/04. Rear axle 75w-90(trailer towing 75w-140).

kj924 said:

See....my front axle specs 80w-90 and mine is an '04 build date 5/04. Rear axle 75w-90(trailer towing 75w-140).

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Weird, from Jeep's Website, I downloaded the PDF owner's manual and it states:

"Axle Differential (front-rear) Mopart SAE 75W-140 (API GL5) Synthetic Gear Lubricant or equivalent.
The 8.25 Corporate Rear Axle should use a SAE 75W-90 Gear Lubricant.
For trailer towing, the lubricant should be replaced with SAE 75W-140
Synthetic Gear Lubricant. Models equipped with Trac-Lok™ require a friction
modifier additive."

That is exactly what my owner's manual states as well.

What is the big difference between 75w-140 vs 80w-90 anyways? One is a syn, vs dino, but what about the weights? Does it really make that much of a difference? I'm just curious.

osufans said:

What is the big difference between 75w-140 vs 80w-90 anyways? One is a syn, vs dino, but what about the weights? Does it really make that much of a difference? I'm just curious.

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The difference is mpg's.

75w-140 synthetic gear oil will still be thinner then 80w-90 dino gear oil,don't believe me buy a bottle of each and stick in the freezer for 1 hour and see what one pours out faster.It's all about mpg's to meet federal mpg standards,the bad news is synthetic gear oil(only applies to gear oil) does not effectively lube diff gears and bearing like good ole dino gear oil does and require more frequent changes then dino gear oil.


Obama's ******* just signed into law that auto makers must increase there combined mpg's # by more then 10mpg's more then currently mandated by 2016.Expect cheaper made parts,lighter parts that wearout faster,and most likely using engine oil in the diffs to reduce friction.All will result in more frequent fluid changes and short lived part lifes.

tjkj2002 said:

the bad news is synthetic gear oil(only applies to gear oil) does not effectively lube diff gears and bearing like good ole dino gear oil does and require more frequent changes then dino gear oil.

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I would suggest that folks do their research on this one. For starters, call the tech line of your favorite lube mfr.

tjkj2002 said:

Obama's *******

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Now THIS, I agree with wholeheartedly!

belvedere said:

I would suggest that folks do their research on this one. For starters, call the tech line of your favorite lube mfr.

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Oil tech lines will tell you want you want to hear and not the truth.It's all about mpg's and thinner does not make it better,just improves mpg's but with a few strings attached.

Yeah, I know your opinion. I also know there are diff builders who trash syn lube, just like there are some engine builders stuck in the past who offer dire warnings against syn oil. I am old-school in alot of ways, but today's oils/lubes are light-years ahead of the old stuff.

Like I originally said, though, folks should do their own research, instead of just reading some internet post. I suggested calling their favorite oil co's tech line as a starting point, not as a final authority. Most importantly, talk to people who run a syn diff lube, and see how it works for them.

My local transmission shop, which has worked on my previous jeep's T-case - and are trustworthy - has refused to change the diff fluid in my Liberty with only 35k miles on the fluid. He checked the fluid and said it looked good. This is a street vehicle for me. It does not see rivers or off roading. I believe many other here are in the same situation where 12-15k miles is overkill.

mberthia said:

My local transmission shop, which has worked on my previous jeep's T-case - and are trustworthy - has refused to change the diff fluid in my Liberty with only 35k miles on the fluid. He checked the fluid and said it looked good. This is a street vehicle for me. It does not see rivers or off roading. I believe many other here are in the same situation where 12-15k miles is overkill.

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Your front diff still turns even when not in 4wd,still sees all the heat cycles that the rear does so should be changed at the same time as the rear.

tjkj2002 said:

Your front diff still turns even when not in 4wd,still sees all the heat cycles that the rear does so should be changed at the same time as the rear.

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I have a question about this though...why does the rear even need to be changed at 12K-15K? This is the first "truck" I've ever owned that recommends changing the rear diff fluid any sooner than 30K, and most only recommend every 60K (from what I recall anyways...Ford F150, Ford Ranger, and Dodge Ram.)

Just curious why so often? Is it due to the "trail" rating, and therefore it is assumed it will be driven as such, so therefore to assure adequate protection Chrysler recommends changing the fluid so often?

Thanks!

osufans said:

I have a question about this though...why does the rear even need to be changed at 12K-15K? This is the first "truck" I've ever owned that recommends changing the rear diff fluid any sooner than 30K, and most only recommend every 60K (from what I recall anyways...Ford F150, Ford Ranger, and Dodge Ram.)

Just curious why so often? Is it due to the "trail" rating, and therefore it is assumed it will be driven as such, so therefore to assure adequate protection Chrysler recommends changing the fluid so often?

Thanks!

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It's the synthetic gear oil,all newer vehicles have about 15k gear oil changes now.

I think a lot of people forget this footnote on the 15k diff fluid change.

"‡Off-highway operation, trailer towing, taxi, limousine,
bus, snow plowing, or other types of commercial service
or prolonged operation with heavy loading, especially in
hot weather, require front and rear axle service indicated
with a ‡ in Schedule “B”. Perform these services if the
vehicle is usually operated under these conditions."

While some folks no doubt fall into this category, I would think the majority of us do not. IOW, while we may do some off-roading, trailer towing, etc, our vehicles are not "usually operated under these conditions".

You are not alone.
Add 1 more to that tally of PROUD preventative maintenance "nuts".

I am an extreme believer in the doctrine of the God of Preventative Maintenance.
Cheers
Auberon

tjkj2002 said:

Your front diff still turns even when not in 4wd,still sees all the heat cycles that the rear does so should be changed at the same time as the rear.

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Agree with you but nowhere did my post say that I was changing the rear oil more often than the rear. They both get changed at the same time - when necessary. 12k miles is not necessary...