What gear oils?

[Georg]

I drive a 07 CRD (2.8) Ltd. At 40000mi I will be changing all gear oils (diffs, transfer, transmission). I have been recommended by the independent Jeep guy who will take care of this to fill both diffs (front/rear) w/ 75W-140 rather then the recommended 80W-90 / 75W-90 (f / r). Reason is that in high summer temps (such as in the south) the diffs overheat with the thinner oil. He claims that diff paint flaking off as he has often seen is due to overheating.

Any thoughts/recommendations?

 

[tjkj2002]

Non-synthetic gear oil,80w-90 or 85w-140.Your choice,both work but for offroading and towing better to use 85w-140 in the rear diff.


Skip any synthetic gear oil,bad for your diff,good for mpg's but that is it.

 

[Georg]

Non-synthetic gear oil,80w-90 or 85w-140.Your choice,both work but for offroading and towing better to use 85w-140 in the rear diff.


Skip any synthetic gear oil,bad for your diff,good for mpg's but that is it.

So you are OK with the -90, but would not go to a thinner "cold" oil (75W)?

Why not synthetic? I thought viscosity is the determining factor. In other words a 75W-140 is a 75W-140 (OK, with some leeway) and synthetic will only maintain its properties longer.

 

[tjkj2002]

So you are OK with the -90, but would not go to a thinner "cold" oil (75W)?

Why not synthetic? I thought viscosity is the determining factor. In other words a 75W-140 is a 75W-140 (OK, with some leeway) and synthetic will only maintain its properties longer.

Everything that makes synthetic oils better is actually worse for your diffs due to how the diffs oil themselfs.Better flowing is not what you want,you want it thick and to resist flowing since your diffs are a splash oiled system so if the gear oil moves to fast back into the pumpkin your pinion bearings(high pinion or lifted low pinion diffs) and axle bearings will starve for lubrication.Dino(non-syn) gear oil also provides better thermo heat transfer in a non-forced oiled system like a diff.

 

[Georg]

So then, even though I do not have a lsd, I should go for a ls oil (I I understand this right, the LS additives make the oil stick to the gear surfaces)?

 

[tjkj2002]

So then, even though I do not have a lsd, I should go for a ls oil (I I understand this right, the LS additives make the oil stick to the gear surfaces)?

No need if you don't have a LSD.

 

[Georg]

OK, thanks

 

[LetFreedomRing]

Non-synthetic gear oil,80w-90 or 85w-140.Your choice,both work but for offroading and towing better to use 85w-140 in the rear diff.


Skip any synthetic gear oil,bad for your diff,good for mpg's but that is it.

What's your opinion on synthetic blend? Only reason I am asking is for us that have colder temperatures in the winter. This past winter I nearly stopped when shifting between 1st and 2nd gear at slow speeds due to thick fluid. Once heated up it wasn't as bad. Currently I am running 85w-140 dino in both diffs.

 

[tjkj2002]

What's your opinion on synthetic blend? Only reason I am asking is for us that have colder temperatures in the winter. This past winter I nearly stopped when shifting between 1st and 2nd gear at slow speeds due to thick fluid. Once heated up it wasn't as bad. Currently I am running 85w-140 dino in both diffs.

Use 80w-90 in the front.I have no issues when below freezing,or below 0 degrees, but I do have front lockouts.

 

[tommudd]

I use 80-90 in the front and 85-140 Dino in the rear and never have any issues

 

[LetFreedomRing]

Cool, thanks. Any brand recommendations for dino oil? I have Coastal gear oil in it now...

 

[TheBlueKJ]

Cool, thanks. Any brand recommendations for dino oil? I have Coastal gear oil in it now...

I'm going to be using valvoline next diff fluid change