I have a 95 f250 psd that I want to change the fluid in the front and rear differentials. The manual that comes with the truck only lists a ford part number. I bought 85/140 Rottela to put in it but was wondering if it should be 80/90 weight. Thanks, Todd

 

80W/90 is listed as the correct axle lube. Might as well put in the stuff called for in the manual since this is a fairly time-consuming job.

To drain the rear differential you need to pull the cover off. Before pulling the cover, make sure that the fill plug is not rusted or frozen in place! There is no easy way to drain the front differential. A suction hose through the fill plug is probably the best method.

Lou Braun

 

Thanks, I'll take the other stuff back and get 80w/90. I don't recall if there is a gasget involved here or not. If I remember correctley I saw a posting here that said something about cleaning the mating surfaces with carb cleaner and using RTV or sylicone. Is this correct? Thanks, Todd

 

75W140 synthetic is the optional fluid for the rear. Either RTV or gasket should work fine. In my last axle I reused (left it there) the gasket, the previous one had RTV, so I used the same.

 

just a reminder, if you have limited slip diff you should add a friction modifier to your diff fluid too.your local ford dealer will have it -billy

 

Billy, I tryed my trucks 4x4 today to see if the front hubs were working ok. It snowed here this week, And I have not used them for a few months. Not to much time to play this year. Now I find that the rearend does not lockup. Just one wheel spins,I did this on a snow covered hill on the farm. Tryed several times. Do you think changing the fliud would help? It is a 78, 160 miles and I have only had it 3 years. Thanks, Erv

 

ERVIN,it would nt hurt to change your diff fluid.especially if it has not bin changed for a while.examine the oil for metal fillings,or other forein matter at that time too.if you have the cover off,i always like to do a visual inspection with good lighting of the gears,bearing caps,axles,all the bolts,and the housing for cracks too.i rotate the diff a couple full revolutions while examining it so i get a real good look. then refill the diff with new fluid and friction modifier. i would run the truck a day or two,then see if its better.if i still only spins one tire like an open diff,i would check and see how much torque it takes to rotate only one tire with a torque wrench while the other tire is on the ground still.i dont know what the specs are for your trucks diff clutch pack would be,maybe some one here could post it for you.if your clutch packs are worn out ,it wont harm your diff at all, it just means your diff will act like a open diff,not a limited slip diff.if thats the case,and you dont feel like replacing the clutch packs at this time,your ok.at least you will know what it looks like in the diff,and the oil is new too. hope this helps.-billy

 

Thanks Billy, Do you clean it out with anything before you put it back together? Erv

 

ERVIN,i use solvent,but only new,unused solvent,so there are no contaminants to worry about.then i wipe all the componants with a clean,lint free rag,i rotate the assembly and wipe all the teeth individually,the carrier,the diff housing ,side gears,everything,take your time,and keep looking for cracks or chips in gears,its part of your inspection sort of.make sure there are no rag particules left in there,then either replace the diff cover gasket,or just use rtv silicone as a gasket.then fill it with oil and friction modifier,check for leaks,done.-billy

 

Thanks again, will give me something to do Monday, it is going to go to 70 here so I had better get my stuff lined up to get it done. Like I needed more stuff. Ha! Erv

 

How can you tell if you have limited slip or not? 95 f250 psd 4x4. Thanks Todd

 

if you take the vin number an post it imsure there will be someone here that can break it down and tell you the diff type.or just go out,jack up your truck,with both rear tires off the ground,spin one tire by hand.if the other tire rotates in the same direction its limited slip,if the other tire rotates in the opposite direction,its an open diff.-billy