blupupher

iTrader: (2)

Did you use a Friction modifier last time? Even though Mobil 1 has LS additive, it is not enough for the Ford LS. You could just try adding some XL-3 LS additive.

I have used Lucas 75w-140 with no issues, have Valvoline 75w-140 in my brother in law's F150, and Walmart Supertech 75w-140 in mine now.
I used the XL-3 in all of them.

OhioLariat

If you didn't add friction modifier at the time of fluid change, I'd simply do that. As blupher noted, the "built-in" additives are (usually) insufficient. It's also possible, as 2thousand5.4 mentioned, you simply don't have enough in there. Unless you got water in the diff, there shouldn't be anything wrong with the fluid itself.

P.S. From all I've read, you want to use *only* the . No aftermarket/3rd-party stuff.

Andy

CDIESEL

Well I did the fluid change tonight. Also added the ford additive and drove it home 50 miles and it was still doing the chatter when I was pulling in the driveway..

Maybe it needs more additive?

2thousand5.4

You could try another bottle of xl3. Your LS probably needs a rebuild tho. What rear-end do you have? The 8.8 is easier than the 9.75. The 9.75 isn't to bad once you figure it out. It's gonna be about 130ish in parts for brand new clutchs. That's using frpp carbon fiber clutchs. You can have standard ones for less

CDIESEL

That bites if that's the case. Yeah I have the 9.75. Is there a kit you recommend?

2thousand5.4

I used the Yukon kit because my springs where also broke and that's the only way to get new springs.

Jbrew

That's where I'm at with my rear gear and clutches. 300,000 miles, didn't know my LS was out until I could of used it one day lol.

2thousand5.4

Mine wasn't bad after 185k actually. I was just in there doing the gears so I figured might as well do the clutchs too. Then I broke the springs and had to buy the Yukon kit lol. I was just gonna use a standard rebuild

Jbrew

Yea, can't even tell mine is out, acts normal, I kept the fluid changed, used the separate modifier vs the blend. Used Ford spec anyway. Last winter entering a driveway, I stopped full square with my front wheels in the gutter pan just before the driveway. Only one rear tire spun. Had to use my shift on the fly to make it the rest of the way...what a hassle lol.

BrowningSCrew

My 1.75" wheel spacers arrived today. Just have to find some lug nuts and they'll go on tomorrow