Just picked my f150 up after the dealer fixed a badly leaking rear differential cover. With only 1500 miles on it, there were obvious drops of oil on the garage floor, not just weeping around the seal. Anyway, when I picked it up, the service report lists that the diff was filled with 75W-140 Hypoid gear oil. Since the truck has a limited slip 3.55 in the rear, I asked to make sure that they had put in the friction modifier. The service manager said that hypoid oil had the friction modifier in it. Does anybody know wether this is the case or was he just blowing smoke to get me out of his hair.

Thanks for any info!


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Y2K F150 SC 4wd
Trition 4.6, 5 sp manual
Tow Package, Factory CD
No mods yet!

 

To confuse the issue even more, aren't those diffs supposed to have "synthetic" oil?

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1999 Lariat Super Cab, S.B. 5.4L, 3.55 LS
and everything but the leaky slider window.
Bright red w/ gold 2-tone, Leather Captain's Chairs
Mods: Duraliner bedliner, Bugflector II, Hide-a-hooks.
& a leeetle chrome tip on the exhaust.

 

Whytknyt,

I just replaced my differential cover as posted in "other aftermarket". I also purchased hypoid oil from Lubrication Engineering and was told that all "limited slip" differentials need the addition of the friction modifier to the hypoid oil. I was at the Ford parts store recently and low and behold, 4oz bottles of friction modifier were stacked right next to the hypoid oil. For your second question, yes, Ford limited slip differentials come with synthetic oil, with friction modifier added.

P.S. The friction modifier smells really BAD.

 

Hypoid Gear Oil is just what the name says.
There is NO Friction Modifier in any Hypoid Gear Oil that I am aware of.

How much does your differential hold?
How much did the dealer put in?

If he replaced "half" of your Hypoid Gear Oil, you need to have them add about 4 oz of Friction Modifier (1 bottle) just to keep the correct ratio of FM to Oil.

Make sure he notes your concerns on your work-order! That way when they have to replace your LS differential, you'll have proof of why it failed!

Good Luck.

BTW - he was either Blowing Smoke or doesn't know enough about LS differentials to be allowed to work on one.

[This message has been edited by J-C (edited 03-08-2000).]

 

Service managers rarely know much if anything about what was done. It should be listed as parts on your service recipt. If it is not ask why. Ask to speak to the technician who preformed the service. He will know, or at least "should" know.

 

I'm not taking any chances. The friction modifier was not listed on the invoice. So I picked up synthetic lube that met ford specs and 4 oz. of friction modifier that met for specs and drained and refilled myself. Now I know what is in my rear differential.

Lets hope that it is the right stuff, since I'm leaving for 10 days on spring break that will rack up 2500 miles on my truck, more miles than are currently on it!


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Y2K F150 SC 4wd
Trition 4.6, 5 sp manual
Tow Package, Factory CD
No mods yet!

 

Two types of Primary Gearing (aka the Ring and Pinion) are commonly used in rear ends - Spiral Bevel and Hypoid. The Spiral Bevel gears mostly 'roll' over each other, whereas the Hypoid gearing tends more to 'slide' as well as roll over each other, with the latter needing the Hypoid Gear Lubricant -- which contain friction additives to help prevent wear during the sliding.

For an example of a synthetic lubricant capable of handling both types of gearing, peruse: http://truck.eaton.com/na/eaton_pdfs.../tcsl-0002.pdf and for general info on lubrication application, see: http://truck.eaton.com/na/service_pr..._requirements/



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Y2K XLT EC 5.4L 7700# SB 4x4 w/LS 3.73 (repeat buyer)

 

Hypoid gear oil is not necessarily the friction modifier. Hypoid is simply for extreme pressure gearboxes, which is good in a differential. However, unless the friction modifier was added or the lube he used already had the modifier in it, such as in a specific differential locking fluid, it probably doesn't have the modifier.

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'97 Ford SC 4X4 XLT Off Road pkg., 4.6,A/OD, 3:55, premium sound w/CD chg, Black clct,towing pkg., hvy duty elec. pkg., Bridestone dueler AT's, line X, Flowmaster true duals, chip, K&N air filter, smittybilt stainless nerf bars