motodog

I am waiting for paint to dry on Rear Diff Cover, and I have a nagging question!

I got 3 qts of Syn Vavoline 75-140 Full Syn AND the 7 oz. tube of
Friction Modifier (Trans-X?) from Autozone.

The rear end was chattering. The Valvoline says it contains some
Friction Modifier. The Friction Stuff says it mixes with both dino and syn
gear lube, they say put the whole tube in.

Since I don't know if I need it, could it try it without the 7 oz, not filling
the diff up all the way for a tryout day?

I don't want to fill it all the way, since there is no drain plug and it don't
have a siphon?

By the way, the factory RTV was so strong, I could not get the cover off.
It took a flat screwdriver and a ball pean hammer.
I bent the diff cover and scarred the machined diff surface!
I had to flatten the cover and file the burr off on it!

What a bad deal Ford did to save a gasket!

I got a gasket now and will use Gasket Cinch to make sure it is
not glued on again. The RTV was so thin and STUCK, there was no place to get a screw driver in between the cover and diff.

Mike
2005 5.4L 4X4 Supercab LS 9 3/4 Rear End

07lftdstx

If you have a limited slip rear end you NEED friction modifier, stops the clutch packs from burning up and chattering.

kozal01

iTrader: (2)

Use it.

bobkyle2

Yes, Use the friction modifier.

scobar

iTrader: (4)

Use it for sure.

jrmongi

Use it and if your rear I acting up use a second one

motodog

Thanks Everyone,

OK, even though the Valvoline Syn indicates it is not needed, I should put it in.

I hope it doesn't make it slip too MUCH when I need it off-roading?

I will do it in the am.

Mike

motodog

Here is the gear oil ad:





SynPowerŽ Full Synthetic Gear Oil

Formulated for ultimate protection and performance

• Contains additives to assist in protecting gear teeth
• Maintains excellent low temperature fluid protection down to -50°F (-46°C)
• Provides outstanding thermal stability for cleanliness and longer service life
• Contains special additives to reduce chattering in limited-slip differentials
• Recommended for (conventional and limited slip) manual transmissions where an API GL-5 or MT-1 fluid is specified
• Protects parts from rust and corrosion
• Compatible with conventional gear lubricants

allinon72

You already have it, use it.

lariat05.4

Just like everyone says use it. I used the exact same stuff when I did mine. I called valvoline and they said to add an extra 4oz to bring it to ford spec. Straight from the guys at valvoline.