What kind of diff oil

[rondog]

I have a '97 F 250. It has the limited slip rear diff., 4:10s. The manual says 80/90wt (thermally stable) and 8oz. of "friction modifier", Part # C8AZ-19B546-A. Ford Spec. # M2C118-A

What is this? Is it really needed? Is it whats already in limited slip 80/90 that I can get at my parts store?

I'm not interested in the synthetics. I like the old stuff, I just want the right one. Thanks in advance.

 

[drillin001]

you need the friction modifier for the LS to work properly

 

[rondog]

Ok. Will a parts store have this or is it from the Ford dealer only?

 

[Crumm]

Ford dealer only if you want to use the specified stuff. I think auto parts stores do sell some stuff but from what I understand it is not the right stuff. I have always purchased mine at the Ford dealer. Some guys will also tell you that it is not needed but others say it is. I have never changed mine without adding the Ford Friction Modifier so I don't know how it would work without it.

 

[rondog]

Good enough for me. I just finally got to 100,000 miles, after 10 years. So it needs changing now. Thanks for the help.

 

[bushpilot]

you need the friction modifier for the LS to work properly

not if you use the royal purple synth. stuff !

 

[95_stroker]

I'm not interested in and synthetics. I like the old stuff, I just want the right one. Thanks in advance.

not if you use the royal purple synth. stuff !

I guess that settles that!

 

[bushpilot]

I guess that settles that!

maybe...but i dont get the opposition to synth. 'specially in
"locations" where the fluid is rarely changed...its not like ford
makes their own lubes or is KNOWN for formulating and making
their own.

so he can get under-performing products at a higher price... w/ a
ford label on the bottle....

yup...guess that does settle that !

 

[95_stroker]

maybe...but i dont get the opposition to synth.

yup...guess that does settle that !

To each their own eh?

 

[rondog]

Well, I thought I could drain the old oil out through a drain plug and refill through another. That is why I was going to use the dyno oil.
It looks like I have to remove the whole cover. So I'll be able to clean it all out and install synthetic oil.
Any recomendations?
I also need to change my pinion seal. It's leaking a bit.