Post Gear swap maintaince question.

I swapping my gears out next weekend and seeking advice. It's a 2015 JKU HR with stock D44 front and rear. 1. How many miles should drive until I need to replace diff oil? 2. What type of oil do think is the best. 3. When changing the oil out after the break-in period do I need to completely drain the housing by removing the diff. Cover or would just using the drain plug be good enough? Thanks in advanced for your input!


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thechrisjones said:

I swapping my gears out next weekend and seeking advice. It's a 2015 JKU HR with stock D44 front and rear. 1. How many miles should drive until I need to replace diff oil? 2. What type of oil do think is the best. 3. When changing the oil out after the break-in period do I need to completely drain the housing by removing the diff. Cover or would just using the drain plug be good enough? Thanks in advanced for your input!


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Most gear manufacturers recommend 500 miles. Your gears may even come with a break-in instruction guide or you can find it on the gear supplier's website. Go with what the vehicle manufacturer recommends as far as oil. If it's an open diff, the cheaper the gear oil the better as they're all pretty similar. If you have a locker, do your research and find out what oil works or doesn't work. As you go with smaller gears (5.13 or 5.38) you should use a little bit heavier oil to compensate for the generated heat. Honestly, I would drop the cover after the 500 miles, the crap that comes off of the gears is really black and nasty. It's worth taking the time to clean the inside really good with brakeclean and inspect your new gears to make sure they're all good.

^That's what I would do.

thechrisjones said:

I swapping my gears out next weekend and seeking advice. It's a 2015 JKU HR with stock D44 front and rear. 1. How many miles should drive until I need to replace diff oil? 2. What type of oil do think is the best. 3. When changing the oil out after the break-in period do I need to completely drain the housing by removing the diff. Cover or would just using the drain plug be good enough? Thanks in advanced for your input!


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Click to expand...

WJCO said:

Most gear manufacturers recommend 500 miles. Your gears may even come with a break-in instruction guide or you can find it on the gear supplier's website. Go with what the vehicle manufacturer recommends as far as oil. If it's an open diff, the cheaper the gear oil the better as they're all pretty similar. If you have a locker, do your research and find out what oil works or doesn't work. As you go with smaller gears (5.13 or 5.38) you should use a little bit heavier oil to compensate for the generated heat. Honestly, I would drop the cover after the 500 miles, the crap that comes off of the gears is really black and nasty. It's worth taking the time to clean the inside really good with brakeclean and inspect your new gears to make sure they're all good.

^That's what I would do.

Click to expand...

I agree with WJCO

1) MOST companies recommend a 500 mile break-in followed by a fluid change. Check your gear break-in paperwork
2) The best diff fluid is the cheapest diff fluid that meets the required specs. I'm running Valvoline 85w140 in my 2015 JKUR HR with 5.13s.
3) I removed the diff cover, Spreayed everything down with brake cleaner, wiped everything down with a clean rag, cleaned up the diff cover, used "The Right Stuff" to seal everything back up, then fill it back up with fluid. easy :thumb:

Looks like the guys above have got this one covered :thumb:

The only thing I would add to is that during the 500 miles, you take it easy on the speed especially if you are running 5.13's or higher.

Got it! Thank you very much


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500 mile break in like others have said plus the following - this is recommendation from gear manufactures/installers:

• On initial run, drive lightly for 15 to 20 minutes then stop to allow differential to cool completely for 20 to 25 minutes.
• Keep the vehicle at speeds below 60 mph for the first 100 miles.
• Avoid towing and heavy acceleration, as well as vary speeds every 5 to 10 minutes while driving on highways.
• Drive conservatively and do not drive more than 50 miles at a time without allowing a cool cycle during the first 500 miles following installation

First time towing should be limited to light load for no more than 15 miles, then allow differential to cool completely for 20 to 25 minutes.
• Repeat this procedure for first 45 miles of towing for full break-in of gears for towing vehicles.

EVO recommends under 65mph and easy on the skinny for the first 500, just had mine done. Not sure you need to let them heat up and cool down that much though.

I did the above- 15-20 miles with a full cool down. Since my shop was 50 miles from home, I took a stop at the USMC museum for a tour to let the gears cool. Then after 500 miles, drained and refilled the lube. 75-90 front, 75-140 rear since I tow. That stuff was $20 a quart!