Rear axle lubricant

[Mr. Hemi]

Changing the rear axle lube in my Dana 70 and was going to switch over to synthetic. The stuff I bought is Mobil 1, any good?

Or should I stick with the Pennzoil we used for the past twenty years? Have had good experience with Pennzoil products.

 

[Steve Campbell]

Mobil 1 will work fime IMO

You already have it, so go for it. I do not have any personal experience with Mobil 1.



Not to get too far off of the subject but, I think those of us who "worry" about this sort of thing will have fewer lubrication problems than those who don't. If I am running a marginal oil (not) and am paying close attention (as you seem to be), we will probably have fewer long tem problems than the person who believes the "lubed for life" hype from the dealer(even if the truck came with synthetic).



Back to the topic, has your oil looked "bad" after any of the previous changes, or are you just an inquiring mind?

 

[Cooker]

The Mobil 1 is definitely better than the Penzoil. I have never seen Penzoil synthetic gear lube, but I assume they must make some.



Mobil 1 has worked fine for me for ~ 20,000 miles. I will be changing it again soon so I will get an idea of how well it has held up, and I probably won't use Mobil 1 again. The only reason being I think I am switching to a 75w140.

 

[LSMITH]

Hemi, I have about 50K miles on the Mobil 1 75W-90 in my diffs and it still looks great. There is no garbage on the magnet and temps are low. It NEEDED friction modifier in my truck, so grab a bottle from the dodge dealer to have on hand when you change.



Cooker, if you like the Mobil brand they do make an 80W-140 full synthetic gear oil.



Personally I do not think there is a better gear lube out there than the Mobil products.

 

[Fatboy]

LSMITH,

I am with you. I installed the Mobil 1 75W-90 at the same time as my Mag-Hytec cover. You gotta love that dipstick.

 

[Cooker]

LSMITH,



Thanks for the info. I haven't decided on a brand yet. I went with the Mobil 1 because it was easily available and inexpensive. Maybe I'll check it out the 140.

 

[Turbo Thom]

I know y'all didn't ask about Series 2000, but that has been in my rear end for 85k miles. I check it often and check the mag. on the dip stick. It is still blue and have found no residue on the mag. . The temps have never gone up and I have burned up 3 trannys. I just feel the synthetic oil is the way to go no matter what is said. Like laxt week I was talking to a Cummins rep and he ask me what oil I was using. I told him Amsoil 15W-40 Syn. He said Cummins does not recommend syn. Not that they won't but not now. I told him we were ahead on him now because we were using it now.



I t works.



. . Preston. .

 

[dseabaugh]

synthetic

bottom line is that you use a synthetic. I had regular gear oil in mine and checked the oil to find that it had burned completely black.

 

[Joseph Donnelly]

LE607 is petro based, SAE 90 wt, but premium quality. I just dyno tested it (and yes I bought it, it wasn't given to me to test!) and it was about as low on drag as a synthetic diff lube of 75-140 wt. Given the relatively low ambient temperature these days, that is quite good for a 90 wt. vs. a 75 wt lube. Their product literature shows test results that places it with or above the synthetics--just another option for you when you look at lubes. Two advantages of petro lube, if sufficiently refined, are (1) naturally swells seals so they don't leak; (2) less chemically reactive especially to heat and moisture than the esters generally used as synthetic base stock. BTW, these are the two reasons I bought the LE. Twice I have had to buy new brake shoes, seals, and lots of spray-can brake cleaner due to seal leakage with synthetic lube.



For me the bottom line is: use a good lube and change it regularly.

 

[JJW_ND]

Disagree on the Synthetics and Rear Seals!

In my case, (96 5sp) I had a left rear seal leak at 26K just prior to switching the synthetic 75w90. The 75W90 full synthetic fluid was changed at 28K, 87K, 124K, and 167K. I just got a sample back with 40K on the oil with all wear metals very low. TAN ok.



This differential has seen from -30 to 120 in a matter of hours and then back down again and everthing inbetween. Im sure it has seen 200+ degree in the summer many times. It has seen lots of hotshot loads and lots of ugly arctic cold. The right seal is still factory at 206K. Everything inside is still factory includeing LSD that works like the day it I first drove it.



I can't believe I am just lucky. I have had to good of luck with Synthetics given the punishing temperatures and use my truck has went through.



jjw

ND

 

[Dbonzi]

Turbo Thom

What kind of oil were you running in the tranys. I see You have went through three of them?



Dennis

 

[amsoilman]

Joseph,

I don't know what kind of testing you did, or how many dollars you spent, but I read an article in a magazine called "Overdrive", the issue was 1992. This is a magazine specifficly for truckers. The article was addressing engine oils and transmission and axles.

Here is what was said.

Correct Lubrication is critical to the life of truck transmissions and axles. Selecting the right lube will greatly enhace life and downtime. Because of its critical importance, Eaton and Navistar both firmly recommend the lubes used in transmissions and axles should be more expensive, but more reliable synthetics. Eaton reached that conclusion after Years of Testing and backs its recommendation with High-Mileage Warranties. [End QUOTE] The article went on too say,

Eaton's Fleet Testing led to the company introducing its own Synthetic transmission and Axle lubes. That was 5 years ago! Now remember, the article was written in October of 1992, so the testing must have been way before that. Oh, BTW, they also went on to say that the synthetics didn't "Oxidize" as much, so therefore the seals don't build-up carbon at the lip. Providing bearings do not get slack, the seal lasts the lifetime of the components it serves.



I have also read that all oils, have to have additives to address the seal swell issue. The additive is the same in both petrolium and synthetic lube.



My . 02 worth



Wayne

amsoilman

 

[Turbo Thom]

Dbonzi:

I was using series 2000 on the first at 196K. The other two was sny-torq from Castrol. As of now I'm on the forth transmission and will change back to series 2000 when the fast-coolers go on. Milage is 230K now.



. . Preston. .

 

[Mr. Hemi]

I think I will switch it over to the mobil 1 when I change over and through a tube of limited slip additive to top it off. Just was a little leary of going synthetic in something that has had petro-based lube for in it for so long. Thanks much.