Differential oil change

[CarbonSteel]

That's easy. Capture a mid-drain sample of the gear oil, when warm, using a clean bottle. Use a separate one for each axle, if relevant. Send the bottle(s) to Blackstone Labs for analysis. Better yet, request a free sample kit or two in advance so you do everything right.

By way of example, Blackstone determined that the factory oil fill in my new JLU was "closer to 5W-20", which I found curious since the only specification for the 2.0T is 5W-30.

An UOA will not tell you exactly what oil you have (except perhaps what viscosity it may be), but if you have a VOA of the same oil for comparison you may be able to sleuth it and have a better idea of what it may be.

Closer to a 5W-20 after how many miles? The 2.0T is direct injected which means it typically suffers from fuel dilution which reduces the viscosity and all oils shear to a degree. In addition, there are "thin" and "thick" xW-30 oils so all of this has to be taken into consideration.

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[DanW]

Most of my posts are aimed at young guys/gals and other's that are not set in their ways so to speak.... that would benefit from learning current ways of doing things... that want to know an easy way that is aok to do..

I don't usually make one sentence comments that do nothing to help anyone so to speak.

Your comment tells me... that you don't do ... have not done many, diff oil changes....

I probably do 10 diff fluid changes on Jeeps per month in the Summer months and have done so for years and years.

Sure, as I mentioned ... you can use a pump or a squeeze bottle.... I did that for 50+ years.... but no way is it easier to do with either of those, then it is to do the deed with a pouch.

With a hose on a bottle, or a pump, probably 75% of the time +- you end up with a mess....(hose pops loose cause fluid is real thick, slippery or....) you clean up the mess and also have to clean up the hose and store a hose, yada yada... Not so with a pouch... In the end why not buy fluid in a pouch or save a pouch for next time use...

To each his own... personally I don't care what guys / gals do... personal choice..

I kept an empty Flex Fill bag and poured old Super tech I had in my cabinet into it and filled my differential. The bags are outstanding. Much better than a leaky $10 pump.

 

[Mike8194]

I have the LSD/tow package, and just went ahead and did mine tonight at 5,200 miles. The back was very black and smelled burnt, but no metal chunks and not much sludge on the magnet. Used the Valvoline flex fill 75W-140 for the rear and 75W-90 for the front. The entire process took all of about 30mins. The front really didn’t need to be changed, but now I know. Kept the bags for next time too. Another win for the forum team. Don‘t know what I would do without the brain trust!

 

[jellis4148]

Okay, so I have read almost every post on this thread. I have a 19 Rubicon. The manual states 75w-85 for front and rear. I have read several people say if it has a tow pkg to do 75w-140. No where in my manual does it say to add that if you are towing. Please show me where it says that or explain why you are using thicker fluid that is not recommended? My point is I have put 75w-85 in front and rear on both of my services. What is wrong with using that 75w-85 in rear like the manual says?

 

[jellis4148]

Off road use. Going to Moab in Octobe, and no towing. No where in my manual does it say that. Must have amended in for 20 or 21 models.

 

[jellis4148]

Even in service it says use 75w-85 in the parts catalog. I work at a Jeep dealer.

 

[jellis4148]

So, I checked the manual on a 2021 Wrangler, and it says the same thing. What am I missing. Not trying to be an ass. I'm keeping this Jeep forever. She's my baby. Hell I even tell her goodnight before I go to bed. I want to do what's best for the vehicle. So, I'm just curious why I would use something besides what manual says? Someone posted a manual a minute ago, and it got deleted. Not sure it was for a Wrangler though. It showed specs for a 2.2 engine, and Wrangler doesn't have 2.2 Diesel, at least not in US. I think that manual is for the U.K. version.

 

[entropy]

Okay, so I have read almost every post on this thread. I have a 19 Rubicon. The manual states 75w-85 for front and rear. I have read several people say if it has a tow pkg to do 75w-140. No where in my manual does it say to add that if you are towing. Please show me where it says that or explain why you are using thicker fluid that is not recommended? My point is I have put 75w-85 in front and rear on both of my services. What is wrong with using that 75w-85 in rear like the manual says?

Nothing wrong if not towing.

 

[jellis4148]

Nothing wrong if not towing.

Thank you. Why put the 75W-140 if towing? It doesn't say to. I know we all have things we do that others don't. Hell, I still change my oil every 3,000 miles. Everyone says I'm nuts, but I still do it. I'm fixing to change my front and rear diff oil next week. If doing the75w-140 is advantageous I'll put that in.

 

[OllieChristopher]

John you are going to be perfectly fine using the heavier weight diff fluid.

My local differential shop (Unitrax) uses 76MPB oil 85w140 in every gear change and diff that comes through their shop unless customer wants something different.

 

[jellis4148]

John you are going to be perfectly fine using the heavier weight diff fluid.

My local differential shop (Unitrax) uses 76MPB oil 85w140 in every gear change and diff that comes through their shop unless customer wants something different.

Thanks, I'll probably just stick with what the book says. It's been fine so far with it in it.

 

[OllieChristopher]

Thanks, I'll probably just stick with what the book says. It's been fine so far with it in it.

As per factory service manual page 539 JL Wrangler: We recommend you use Mopar Gear & Axle Lubricant (SAE 75W140)(API GL-5). It is unto you to decide. The reality is it's not going to make a bit of difference.

 

[jellis4148]

As per factory service manual page 539 JL Wrangler: We recommend you use Mopar Gear & Axle Lubricant (SAE 75W140)(API GL-5). It is unto you to decide. The reality is it's not going to make a bit of difference.

That's only for the M200 rear diff which is the Dana 35. I have the 44.

 

[OllieChristopher]

That's only for the M200 rear diff which is the Dana 35. I have the 44.

All the more better to use a heavier oil that has thicker film and higher wear resistance. I would trust a company that does differentials day in and day out more than I would a service manual.

 

[jellis4148]

that manual is for U.K. Jeeps. That’s why it shows a 2.2 Diesel. The Manual pics I’m posting are US. No where in the US manual does it say use 75w-140 for the Rubicon Dana 44. Only for the M200/Dana 35 does it say use it. I’ve looked at all the US manuals from 18-21 and no of them say that. I’m not saying 75w-140 is good or bad. I’m just wanting to use the best fluid for long life, and I’m assuming what they put in the manual is that. They test vehicles with fluids and want you to use what’s going to save them warranty repairs. If 80w-150 was the best they would’ve put it in my manual. Maybe in the UK something is different.

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