ok,i posted a long time ago because i went to the local quickie lube for an oil change and they recommended a diff. fluid change also.To make a long story short,they put 85w90 in the diff,NOT the 75w140 ford calls for.So my question is,how easy is it to change the diff fluid myself and do you guys think any damage has/can occur to the diff.My rear tires will screech and shudder when I make sharp turns,i know thats due to improper gear oil and no friction modifier.I have already ordered some amsoil 75w140 gear lube and am assuming it is pretty easy to change.I just have never changed it before and dont want to mess anything up.Also,can I just siphon the old fluid out and add the new without taking the cover off or should I take the cover off.Thank you very much for any replies.

 

You will need to take the cover off...get something from the auto store to seal it when putting it back on...you cant mess anything up just changing the diff fluid...it is easy...i recomend getting a pump and you will probley need more than a gallon but i dont know for a ford...the pump will help alot they are like 12-20$..hope this helps...

 

I agree with kutter, definitely remove the cover. To refill I picked up a funnel that has a lid, a valve and long hose on it. This made refilling a snap and I didn't spill a drop. You can pick up a sealant almost anywhere. It doesn't take much and in fact it is recommended that you only apply a bead that is around 1/4" wide. Also in regards to the Amsoil, I don't know whether or not you are getting the "Series 2000" gear oil or not, but either way, add the Ford friction modifier. I know that Amsoil claims that you don't need one with the Series 2000 oil but I had a slight shudder until I added this.

 

Thanks for the replies.I take it there is probably no damage otherwise you probably wouldve mentioned it.I wasnt sure because of the limited slip and wrong fluid if that would mess anything up.One thing though Kutter,what would I need a pump for if I take off the cover?wouldnt all the old fluid just drain out? Just wondering what you meant.
And Roden,yes I ordered the series 2000 75w140.I will take your advice and go ahead and add ford fric. modifier also.Thanks again guys,I appreciate it.

 

You would use the pump to take the old fuid out(most of it anyway) to avoid having it all come gushing out when you pop the cover off.

You stick the pump's tube in the filler hole and push it in as far as it will go and start pumping the fluid out.It really is simple, but I prefer the messy way (actually my "oil catcher" for oil changes has an opening about a foot wide so none spills in the driveway).

I am going to use redline 80-140 in mine this weekend when I put the new shiny chrome cover on.I can't get amsoil locally and there is no way i will pay 18 bucks a quart for the ford brand.The local shops and parts houses say this will be fine.(its like running 10-30 motor oil instead of 5-30)I also am going too add the ford friction modifier to it even though the redline says " friction modifier usually not required.......but in some cases.......".I would rather not take a chance.

 

The siphon will work, but takes forever and leaves some old gear oil. Remove the pan, drain, clean things up, new sealer, and refill; it's very simple. The first time that I drain a rear end or a AT, I add a drain plug for the future. A rear cover drain won't get all of the fluid out. I usually drill and tap 1/8 pipe plug threads in the bottom/center of the housing.

 

sigh.....take it from a Ford tech....GET RID OF 75W140!!!!!!!!!! This is the worst stuff we have to deal with at dealerships in truck diffs. I have honestly NEVER seen as many differential gear, axle and bearing failures since Ford switched to this crap. The biggest problem with it is that it can't absorb moisture into itself...i'm sure you have pulled covers off of diffs with a couple of years on the oil and it looks kind of rusty. well, it IS rusty! The moisture collects on everything and starts to rust it out. This is the complete truth on the subject-if you don't believe me, talk to any Ford tech who works on trucks that see off road miles. The first thing I did to my SuperCrew was drop that cover and put in some good 'ol 80W90 (and friction modifier, of course) to extend it's life GREATLY. Heads up, y'all.

 

You better check, my service manual called for the 85w90 oil in the rear. Sounds like all you need is the friction modifier. I also had factory LS until I changed to the locker I have now...

doodeeCrew,
I thought I was the only one with a gooseneck 5th wheel. I just completely rebuilt a 1986 Sunline 18.5 ft 5th wheel. Really tows nice and it is great for camping. Everyone just stairs at the gooseneck asking what it is... What kind of trailer you got??