To start off with I know just enough about trucks to be dangerous, but I am pretty handy and can usually fix my mistakes, if made.

My '04 F-350 PSD has 76,000 miles and I figured it was probably past time to change the transfer case and both front and rear axle fluids. I am just wondering how hard it is going to be to do this and if I would be able to do it myself.

If it is worth it to do it by myself or if I have someone do it, I have been hearing really good things about "Royal Purple" synthetic oils and was wondering if I should replace the stock fluid with "Royal Purple". I figure it will probably lower the temperatures and possible maybe even improve mileage some.

Any suggestions?

 

Welcome to the forum!
To make it easier for you in the future, go to "User CP" at the top left of every page and enter your truck info in "Signature". This will appear at the bottom of all your posts so you don't have to keep typing it in. One other suggestion, use the regular size font that everyone else uses, it's just easier to read on some of our old eyes.

There are many, many great threads on anything you want to do, use the advanced search and at the bottom right, select your year after putting in some search terms.

In direct answer to your question, it is quite easy, just make sure you have the right tools and follow directions. Check out this link below, it will give you a great start! Oh yeah, take the diff cover off and clean 'er up and paint!
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hmmm, i am repying so i can see what people say. I am moving to Alaska and I am driving up in Feb so I want to change my fluids as well.

 

the axles are really easy but man does gear oil smell horrible! i would recommend wearing some sort of rubber gloves or something.

 

I just tried to locate the "Signature" option as that was a good recommendation. Couldn't find it. Then searched the FAQ section and learned 25 Posts are required before having access to this feature. So, I'm banned for the time being.

Look's like I need 4 more Posts. And then...

 

I plan on doing mine this winter too. I would think it's a good time to upgrade to the '08 cover as well.

cheers,
Matt

 

Simple task, just make sure you use the the right fluids. Merc V for the transfer case,
75w-90 for the front diff, 90w140 for the rear diff.

 

Correct rear fluid is 75w-140 synthetic. Royal Purple is okay, but it is light in viscosity for improved mileage. I would use Mobil 1 fluids or Amsoil Severe Gear.

 

Make sure you can open the fill hole on the transfer case before dumping the oil!!!

Whatever oil you go with for the rear, if you have limited slip, make sure the oil contains a friction modifier. If it doesn't, Motorcraft has a small bottle of it available.

 

Doohh!! Sorry that is correct, it was very early this a.m. when I replied

 

Check out the tech folder for videos on how to do it. It will walk you through step by step. Welcome!

 

I just changed the fluid in my axles last night, and went with Red Line oils. It was pretty simple.
Somebody brought this thread back from the dead.

 

Changing both is easy and starightforward. I used Amosil ATF in the transfer case (2 quarts) and Amsoil Severe Gear in both front and rear diffs on my 04'. I didn't add any friction modifier to the oil, add friction modifier ONLY if you get chatter.(Of course this applies to a clutch type LS only) I upgraded to the 08' finned aluminum rear cover at the same time. For a sealant I recommend getting some Permatex "Right Stuff" it seals with no dripping or leaks like you can get with some sealants. Don't overfill the diffs or you will get seepage at the pinion seal. If you have a transfer case skidplate be prepared for a mess.

 

That would have been me. Now I only need three more Posts and I'll make the 25 necessary to enable the "signature" feature.

 

I think that the Permatex Right Stuff is the same as the motorcraft sealant available at the dealerships. It is in the the same type of tube for a small caulking gun and cost the same.