Question Changing Rear Diff. Fluid in my F250

[RJDiesel]

I am looking to change my fluid in my rear differential on my F250 and I was looking for some recommendations on fluid and I keep reading about a modifier additive. Any suggestions would,,,,,, as always be greatly appreciated.

 

[majek5]

Use what the manual says for the weight. Most synthetics have the modifier in them already. If you get "chirping" on tight turns, you will need to add some modifier.

 

[Stroked68]

Im actually gonna be doin the same thing to my 99. I bought royal purple oils. Also now would be the time to change out your rear diff cover if its gettin rusty. You can always treat and paint your old cover. I bought a new 08 and up rear diff for the new superduty's cause they are aluminum and have fins. Paid $56 at Ford. Just got to get some longer bolts. Dont forget the black silicone to reseal it.

 

[BIG JOE]

Poke Red Line Synthetic Oil for some info about synthetics ?

I have it my dif & 6 spd tranny. used it for Years & Years. 150K on my 2K. Served me well. No Tranny or Dif failures on anything i've owned.. with it in it.

Lil' pricey but good stuff.

Joe

 

[WD40]

I just changed mine 2 weeks ago, it only had 35,000 on it and it was Royal Purple. It was still real clean. I went back with the Valvoline 75-140 synthetics and it has the modifier already in it. I have the Mag-Hytec Differential Cover on my truck, so it takes 6 qt. at $14.88 a QT. to fill that sucker up. LOL
Doug

 

[BIG JOE]

I just changed mine 2 weeks ago, it only had 35,000 on it and it was Royal Purple. It was still real clean. I went back with the Valvoline 75-140 synthetics and it has the modifier already in it. I have the Mag-Hytec Differential Cover on my truck, so it takes 6 qt. at $14.88 a QT. to fill that sucker up. LOL
Doug

I hear ya Doug. The Redline has been in there.. longer than I like.. for the towing we do. I'm thinking about changing it out.. but it looks as Clean & Clear.. as the day I put it in. (@ 6 qts, @ $16 per)

I drained a bit out of the bottom drain.. (sure like that Mag-Hytec low point drain).. clean there too.. just a fine touch of normal wear.

Joe

 

[Stroked68]

I havnt read my royal purple labels yet but does royal purple have modifiers already in them??

 

[majek5]

I havnt read my royal purple labels yet but does royal purple have modifiers already in them??

Yes it does.

 

[RJDiesel]

Royal Purple?

Royal Purple sounds like the stuff to get for my rig!!

 

[Fine69]

Any GOOD quality synthetic will work fine. Mobil 1, Amsoil, Redline, etc, all make good oils. I've never cared for Royal Purple, just doesn't seem to hold up to all their claims.