2006 Front Diff oil

65thKJ · **Posted:** Fri Mar 30, 2007 11:51 am

I know this has gone back and forth and that the suggested diff fluid weight changed in 2005 to 80w90 from 75w140, so sorry to bring it up again. My questions is: Did anything change w/ the front diff in '05? Did the Dana model change at all or is there some reason that DCX would change fluid weights? I am planning on doing the front diff and the easiest option for diff changes would be the same weight in both diffs. However I like to stick w/ the recommended ratings for most things. I also, want to use synthetic which mostly come as 75w90 and 75w140, so which should I use? I guess my overall question is:
Could a higher weight oil(75w140) do any damage to anything?

sleeve84028 · **Posted:** Fri Mar 30, 2007 12:44 pm

I don't think there were any major revisions to the D30a between any of the model year updates.

I am still a firm believer that the fluid call out from 2002 model year (75w140) was a conservative approach on the engineers part to make sure the realitively small fluid capacity would survive the riggors of daily use. Once there was enough data to support the fluid spec change the engineers went ahead and reduced the requirement a little to the more commonly available 75w90 (or is it 80w90?)... JJ mentioned the benifit of an increase in MPG with the lighter weight fluid and he is probably correct.

I wouldn't have any problems putting in a quality 75w90 synthetic gear oil in both the front and rear diffs.

JJsTJ · **Posted:** Fri Mar 30, 2007 2:18 pm

Any of the good GL5 Fluids in the popular weights of 75w-90 and/or 75W-140 will work fine. I would make sure you use a Full synthetic though.

Amsoil also has a new 75W-110 that exceeds the requirements and would be great in both front or rear diffs. All 3 of my Jeeps will be using it from now on in both diffs.

unixxx · **Posted:** Fri Mar 30, 2007 2:27 pm

65thKJ, according to my dealer, it's fine to use 75W-140 in the front D30a.

John, other than mileage, are there any advantages of 75W-110 over 75W-140?

JJsTJ · **Posted:** Fri Mar 30, 2007 4:04 pm

unixxx wrote:

65thKJ, according to my dealer, it's fine to use 75W-140 in the front D30a.

John, other than mileage, are there any advantages of 75W-110 over 75W-140?

Not really, it is just a nice in-between weight and would be perfect in both front and rear diffs so you wouldn't have to mess w/ two different weights. I honestly have no problem running 75W90 but figure I will just run the 110 in both now. It will probably be at least another year before I switch though as I am nowhere near any mileage on what is already in my diffs.

65thKJ · **Posted:** Fri Mar 30, 2007 6:33 pm

sleeve84028 wrote:

I am still a firm believer that the fluid call out from 2002 model year (75w140) was a conservative approach on the engineers part to make sure the realitively small fluid capacity would survive the riggors of daily use. Once there was enough data to support the fluid spec change the engineers went ahead and reduced the requirement a little to the more commonly available 75w90 (or is it 80w90?)... JJ mentioned the benifit of an increase in MPG with the lighter weight fluid and he is probably correct.

In that case it sounds like the 75w140 wouldn't do any harm, it would just be a little overkill. I do plan on towing occasionally ~2000lb trailer so I'm thinking of doing the 75w140 in both.

2006 Front Diff oil

Who is online