I bought Valvoline in a 5 gallon bucket. This will give me three changes on both differentials. Just one more option to have. When I bought it the price came to about $5.50 a quart (of course I got 20 quarts all at once).

 

The stock 11.5 third member holds 122 oz.

 

I too changed my front and rear diff. fluid today. Thanks for the advice on the many options for synthetic fluid options. The gear sets in my truck looked excellent and so did the factory fluids that were drained today. I did end up buying a new torque wrench - my old "beam style" torque wrench left a lot to be desire when trying to get an exact tightness on the bolts. I guess it's cheap insurance but no guarentee to do the fluid change

I decided to go with the 75W90 weight. I stepped up to a heavier weight fluid on one of my ford superduty trucks and within a few thousand miles I had some major issues. As you might guess ford would not cover the damage due to me not following manufactures spec's

 

If I remember correct dodge put out a bulletin to use the heavier axle fluid if the truck is used for heavy towing.

 

when you guys talk about heavy towing what exactly constitutes heavy towing. Is it a lot of towing with a heavy load over a long distance or is it just pulling a heavy load periodically? I want to change my diffs and am wondering if I should go with heavier fluids.

 

Just my honest opionion - all trucks fall under the severe service definition if you look at it technically. Stop and go city traffic is the big killer. Why not go for heavier synthetic fluids. It's not going to hurt our trucks.

I have Amsoil in everything I own, except my lawn mower......yet. For the low temperatures we get up here, there's nothing out there that remotely meets comparison. I'm running 15W40 Diesel and Marine in my '98 gas truck - it has a lower pour point than Mobil 1 10W30 - no problems, more benefits on engine protection. JMHO again.

 

In my opinion if you are towing anything over 9 or 10K then you are towing heavy. I really think you need the heavier weight oil if if you are pulling that weight. Now I tow 17K so there is no doubt that I tow heavy. As I explained in another thread, I used the MOPAR stuff in mine and the gears went south on me. The new gears got the Redline 75W140 and I have put 12,000 of HEAVY towing on her without a whimper from the rear end. I had a long discussion with the tech who installed the gears and he agreed.

When I first got my truck I contacted AAM axle about the gear lube and in so many words said that there were "definite benefits" to using heavier oils when towing. But they would not come right out and contradict DC. They said those axles were filled with oil that would be suitable for everything from Mexico to Alaska. I figure for the temperatures that I tow in and the weight that I pull it was a no brainer.

Casey

 

I am thinking about switching to Redline in my diffs. My manual tells me that I am supposed to use a friction modifier in the rear diff but the spec sheet on the Redline web site tells me that with their oil no additive is necessary.
Any comments on this?

 

Mexstan,
I am in almost the same boat as you, and sent an email to Red Line Wed. evening asking them for a recommendation. My guess is that their product will work perfect for both our trucks, but will post the info when I receive it from Red Line.

 

i would like to know to because iam getting ready to put the mag hytech on and goin to run the redline 75-140 syn and would like to know if i need the friction mod or not

 

This is the response I received today in answer to my question about which Red Line product to use in the new design differentials in today's Dodge trucks:

Thank you for contacting Red Line Oil, in your Dodge rear
differential and the front differential as well I would recommend the
75W90. This product contains a friction modifier needed for chatter
control with a clutch type limited slip, but also suitable for use
with other limited slip types and open differentials. The friction
modifier as well as controlling chatter, reduces friction and
temperatures.

Regards, Dave
Red Line Oil

I've had good luck with their products in my race car, and intend to follow their recommendations for my truck. Hope this helps others.

 

Is there any reason NOT to run 70/140 in the rear?
I have decided on redline this is the only choice I havent made yet.

 

The information I received today came from Dave Granquist. His email address is: dave@redlineoil.com. Since I never tow "heavy" by the definition here on this site, I have all the information needed to satisfy my curiosity. If others desire more or different information about Red Line products, I suggest they contact Red Line directly. They seem to be a good company to work with, and would likely provide as much information as they can to help their customers.