Hello there. The diff is limited slip w/ 4:10 gears.
I use the Royal Purple 75w-140 Synthetic. It was fine until start leaking from the cover. I Have to do it again.
I remember reading here on the forums to not use Synthetic on the Limited slip??
If, I can use the Synthetic again. I have 3 quarts of the RED LINE Shock proof, I know I need to buy one more.
I've always use RED LINE oil products in my other cars and noticed great results.

Please, tell me your opinion.


Thank you very much.

 

i think it calls for synthetic 75-140w gear oil in the rear diff doesnt it? i run the valvoline synthetic stuff and have no problems....

 

Indy is correct... you should use the synthetic 75w-140 gear oil.. I use Mobil 1.

 

x3 Use the synthetic oil

FWIW, Here's a great write up on the change procedure:

Welcome to guzzle's Rear Differential Maintenance Web Page

 

X4 Changed mine out with RP 75-140 synthetic. I also added the ford friction modifier for good measure. The link Ponyboychris listed above will show you where you made your mistake with the leak. Good luck

 

Thank you guys. "My mistake", was not using enough silicone around the bolt holes, when I look at the cover I see that it's leaking right from the bolts. I'm considering buy the Original gasket from Ford. I hope it will not leak anymore.

Thank you again for the information. Congrats: GUZZLE'S GREAT WEB PAGE.

 

If you use the silicone it will probably end up cheaper than getting anything from Ford. Mine didnt have a gasket as far as I know and Ford used the silicone goop too. I have a 2000 F250 so it might have changed! Just surround the bolt holes and try to put it on as straight as you can and dont smear any...I did mine 3 weeks ago for the 1st time ever....no leaks! Good luck!

 

Guzzle sure has well thought out, well written articles that explain in depth how to properly do a job.

 

silicone will do the trick,I haven't used a gasket on any size rearend up to 50k lb truck rears in 30 yrs

 

<TABLE style="WIDTH: 290pt; BORDER-COLLAPSE: collapse" cellSpacing=0 cellPadding=0 width=386 border=0 x:str><COLGROUP><COL style="WIDTH: 154pt; mso-width-source: userset; mso-width-alt: 7497" width=205><COL style="WIDTH: 136pt; mso-width-source: userset; mso-width-alt: 6619" width=181><TBODY><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-RIGHT: #ece9d8; BORDER-TOP: #ece9d8; BORDER-LEFT: #ece9d8; WIDTH: 154pt; BORDER-BOTTOM: #ece9d8; HEIGHT: 12.75pt; BACKGROUND-COLOR: transparent" width=205 height=17>75W140 HP Synthetic Axle Lube</TD><TD style="BORDER-RIGHT: #ece9d8; BORDER-TOP: #ece9d8; BORDER-LEFT: #ece9d8; WIDTH: 136pt; BORDER-BOTTOM: #ece9d8; BACKGROUND-COLOR: transparent" width=181>Lubermatic OEM Synthetic 70w 140 States on lable meeting spec.</TD></TR></TBODY></TABLE><TABLE style="WIDTH: 170pt; BORDER-COLLAPSE: collapse" cellSpacing=0 cellPadding=0 width=226 border=0 x:str><COLGROUP><COL style="WIDTH: 92pt; mso-width-source: userset; mso-width-alt: 4461" width=122><COL style="WIDTH: 78pt; mso-width-source: userset; mso-width-alt: 3803" width=104><TBODY><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-RIGHT: #ece9d8; BORDER-TOP: #ece9d8; BORDER-LEFT: #ece9d8; WIDTH: 92pt; BORDER-BOTTOM: #ece9d8; HEIGHT: 12.75pt; BACKGROUND-COLOR: transparent" width=122 height=17>F1TZ-19580-B</TD><TD style="BORDER-RIGHT: #ece9d8; BORDER-TOP: #ece9d8; BORDER-LEFT: #ece9d8; WIDTH: 78pt; BORDER-BOTTOM: #ece9d8; BACKGROUND-COLOR: transparent" width=104>WSL-M2C192-A</TD></TR></TBODY></TABLE>

Seal silicon for the cover <TABLE style="WIDTH: 170pt; BORDER-COLLAPSE: collapse" cellSpacing=0 cellPadding=0 width=226 border=0 x:str><COLGROUP><COL style="WIDTH: 92pt; mso-width-source: userset; mso-width-alt: 4461" width=122><COL style="WIDTH: 78pt; mso-width-source: userset; mso-width-alt: 3803" width=104><TBODY><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-RIGHT: #ece9d8; BORDER-TOP: #ece9d8; BORDER-LEFT: #ece9d8; WIDTH: 92pt; BORDER-BOTTOM: #ece9d8; HEIGHT: 12.75pt; BACKGROUND-COLOR: transparent" width=122 height=17>D6AZ-19562-AA</TD><TD style="BORDER-RIGHT: #ece9d8; BORDER-TOP: #ece9d8; BORDER-LEFT: #ece9d8; WIDTH: 78pt; BORDER-BOTTOM: #ece9d8; BACKGROUND-COLOR: transparent" width=104>ESB-M4G92-A</TD></TR></TBODY></TABLE>

<TABLE style="WIDTH: 386pt; BORDER-COLLAPSE: collapse" cellSpacing=0 cellPadding=0 width=514 border=0 x:str><COLGROUP><COL style="WIDTH: 80pt; mso-width-source: userset; mso-width-alt: 3913" width=107><COL style="WIDTH: 64pt; mso-width-source: userset; mso-width-alt: 3108" width=85><COL style="WIDTH: 72pt; mso-width-source: userset; mso-width-alt: 3510" width=96><COL style="WIDTH: 92pt; mso-width-source: userset; mso-width-alt: 4461" width=122><COL style="WIDTH: 78pt; mso-width-source: userset; mso-width-alt: 3803" width=104><TBODY><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-RIGHT: #ece9d8; BORDER-TOP: #ece9d8; BORDER-LEFT: #ece9d8; WIDTH: 80pt; BORDER-BOTTOM: #ece9d8; HEIGHT: 12.75pt; BACKGROUND-COLOR: transparent" width=107 height=17>Limit Slip additive</TD><TD class=xl24 style="BORDER-RIGHT: #ece9d8; BORDER-TOP: #ece9d8; BORDER-LEFT: #ece9d8; WIDTH: 64pt; BORDER-BOTTOM: #ece9d8; BACKGROUND-COLOR: transparent" width=85>35 ft lbs</TD><TD class=xl24 style="BORDER-RIGHT: #ece9d8; BORDER-TOP: #ece9d8; BORDER-LEFT: #ece9d8; WIDTH: 72pt; BORDER-BOTTOM: #ece9d8; BACKGROUND-COLOR: transparent" width=96>1/2 Pint 16 oz</TD><TD style="BORDER-RIGHT: #ece9d8; BORDER-TOP: #ece9d8; BORDER-LEFT: #ece9d8; WIDTH: 92pt; BORDER-BOTTOM: #ece9d8; BACKGROUND-COLOR: transparent" width=122>C8AZ-19B546-A</TD><TD style="BORDER-RIGHT: #ece9d8; BORDER-TOP: #ece9d8; BORDER-LEFT: #ece9d8; WIDTH: 78pt; BORDER-BOTTOM: #ece9d8; BACKGROUND-COLOR: transparent" width=104>EST-M2C118-A</TD></TR></TBODY></TABLE>

Works for me

 

I used the orange RTV stuff from Permatex - no gasket. Worked like a champ.

 

Thank you again. Great people here..

 

Think i used black RTV but shouldn't make a difference. Def. great people here... 25 posts in 2 years? Don't be afraid to ask questions. And you can add a sig now... lets see what ur working with lol