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

[kj924]

I am not sure what type to go with when I change the front and rear diff lube. Who has gone with the synthetic in their diffs? I have the friction modifier already, so when the task comes I will be ready. I just haven't made up my mind on the type ...Dino or Synthetic? Opinions on what way to go? I live in a cold climate half the year...but I don't trailer the KJ on a constant basis.


Thanks everyone!

 

[family KJ]

My rear diff was grumbling real bad....I used synthetic...per the manual. I backed out of the drive and the noise was immediately gone and has been silent since.

 

[kj924]

My rear diff was grumbling real bad....I used synthetic...per the manual. I backed out of the drive and the noise was immediately gone and has been silent since.

Do you find any difference other than the noise had disappeared?

 

[family KJ]

Not really, she was running very well before and had no problems, just that grumbling noise.

 

[kj924]

Not really, she was running very well before and had no problems, just that grumbling noise.

OK Thanks. I am leaning towards the synthetic in the rear for sure, still undecided about the front diff.

 

[belvedere]

I'd sure go for the syn. I used a parasynthetic 75W90 in both diffs on mine.

 

[tjkj2002]

Make sure you change the diff fluids every 15k,more so for synthetic gear oil.It's must,no vehicle running synthetic has a long change interval.Use dino gear oil if you want the longer drain intervals but expect slightly lower mpg's.

 

[HoosierJeeper]

Don't use Super Tech oil from Wal Mart....

I'd just go get the Mopar brand stuff.

 

[kj924]

Make sure you change the diff fluids every 15k,more so for synthetic gear oil.It's must,no vehicle running synthetic has a long change interval.Use dino gear oil if you want the longer drain intervals but expect slightly lower mpg's.

The mpg's is what I was thinking about when changing to synthetic.So, a 75/140 synthetic is the way to go then?

 

[tjkj2002]

The mpg's is what I was thinking about when changing to synthetic.So, a 75/140 synthetic is the way to go then?

I'd be thinking 75w-90 for better mpg's unless you tow or wheel it.
Just remember change every 15k.

 

[kj924]

I haven't looked hard for the lube yet, but I don't remember seeing a 75w-90 synthetic where I was looking. I'll look this weekend.
Thanks Troy!

 

[ptsb5a]

MotoMaster 75W90 full synthetic, or the Q State full synth. Whatever Canadian Tire or Bumper-to-Bumper has on special. Tried the Amsoil gear oil, it was way more expensive and didn't render an appreciable benefit. I change it every 20K kms. Have 125000 on it now and never had any noise or trouble with either diff.

 

[tjkj2002]

MotoMaster 75W90 full synthetic, or the Q State full synth. Whatever Canadian Tire or Bumper-to-Bumper has on special. Tried the Amsoil gear oil, it was way more expensive and didn't render an appreciable benefit. I change it every 20K kms. Have 125000 on it now and never had any noise or trouble with either diff.

WOW!!!!!!!!!!!!!

Someone that actually changes the diff oils like there supposed to,your the 2nd person I have ever heard of that does that(me being the 1st).

 

[ptsb5a]

Troy, I plan on keeping my KJ for as long as it will have me. I believe it's called a regular maintenance schedule for a reason. My honey thinks I'm almost **** about it. In fact, I already have the gear oil, ATF+4 for the t-case and enough oil and filters to last me for a while. I like to make sure that I do the scheduled maintenance like the schedule says. Can I mention "schedule" one more time?

 

[tjkj2002]

Troy, I plan on keeping my KJ for as long as it will have me. I believe it's called a regular maintenance schedule for a reason. My honey thinks I'm almost **** about it. In fact, I already have the gear oil, ATF+4 for the t-case and enough oil and filters to last me for a while. I like to make sure that I do the scheduled maintenance like the schedule says. Can I mention "schedule" one more time?

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).

 

[ptsb5a]

Another reason to write down the date, mileage and keep the reciepts for oil n stuff if you do it yourself. I record all that plus the brand and PN of the filter, the brand and grade of oil, blah, blah, blah, in the little maintenance schedule book. Proof that I did the work. It takes a little extra time but I also write down brake pad replacement + part numbers, belt replacement + part number, u-joint replacement + oh, hell, you get the idea.

The damn KJ cost me enough, might as well maintain it properly. Besides, it's in my blood, everything at work is on an inspection cycle of some sort, whether its captive carriage hours, engine hours, airframe hours, cycles, days, landings, arrested landings, firings....... the list is freaking long.

 

[Idaho08KK]

I run Mopar 75w140 synthetic front and rear with JB diff additive. Works great for me.

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.

No kidding. I see vehicles all the time at work that are severely neglected maintenance wise. I can't believe people pay $20,000-$50,000 for a vehicle and let it go to ***t. Then they ***** that their car broke. Go figure morons.

I am a freak about maintenance. In all the years of driving and owning vehicles, the only major problem I have ever had was a fuel pump go out on my old Ford. I have never had a trans failure, engine failure, diff failure, anything. Preventative maintenance saves money in the long run. That is what most people fail to realize.

 

[diyman]

.... I have never had a trans failure, engine failure, diff failure, anything. Preventative maintenance saves money in the long run. That is what most people fail to realize.

Also it lowers the risk of sudden break downs, which, as anyone knows, happen in the most 'ideal' situations....

I'd rather not imagine that happening to me here at night.... chances are .... Kick.gif
(btw: no, I can't carry the proper tool for that job... )

 

[osufans]

so let me clarify, is 75w90 ok to run in the front? i was just getting ready to change mine and bought 75w140 for the front as spec'd by the manual, and 80w90 for the rear (or something like that.) i wanted to put a syn or semi-syn in the rear too....and they had 75w90, which was cheaper than the 75w140 anyways, but they weren't too sure if i could use it that way. and the 75w140 was about twice as much as the 80w90, which is why i stuck with 80w90.

thanks!

 

[loves_off_roading]

osufans I'd stick with what the manual says:

75w140 Front, 75w90 Rear

I can't remember 100% but I believe it says to use 75w140 on the back too if you do heavy towing/heavy off roading

Go all the way bro get full synthetic