Diff Fluid...

2007_Crown_Vic

Active Member

Aug 19, 2016

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Feb 27, 2023

#1

• Feb 27, 2023

• #1

Hi, I was searching some posts here and there seems to be mixed opinions about diff fluid types and friction modifier. It seems a lot of people say synthetic fluid doesn't, or at least shouldn't need friction modifier. They say to run it and if there is chatter add a bit.

I was planning to use Pennzoil Full Synthetic. Anyone else used this? How did it work for you? Thanks!

 

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Mustang5L5

That is…until I whipped out my Bissell

Mod Dude

Feb 18, 2001

43,138

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224

Massachusetts

Feb 28, 2023

#2

• Feb 28, 2023

• #2

I've run the Mobil 1 limited slip diff oil in my car for almost 20 years now. Been changed a few times. No chatter, no issues and my car still 2-wheel peels with the orginal, never rebuilt clutches.

I've never added additional friction modifier.

 

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2007_Crown_Vic

Active Member

Aug 19, 2016

133

26

48

Feb 28, 2023

#3

• Feb 28, 2023

• #3

Mustang5L5 said:

I've run the Mobil 1 limited slip diff oil in my car for almost 20 years now. Been changed a few times. No chatter, no issues and my car still 2-wheel peels with the orginal, never rebuilt clutches.

I've never added additional friction modifier.

Click to expand...

Thanks. On Pennzoils website they say this has sufficient friction modifier already in it for most applications, and that only newer high horsepower cars may need more. I guess I will use it and just see if it chatters at all. Being a bone stock 1990 GT I think it should be fine...

 

Mustang5L5

That is…until I whipped out my Bissell

Mod Dude

Feb 18, 2001

43,138

17,837

224

Massachusetts

Feb 28, 2023

#4

• Feb 28, 2023

• #4

In the past, folks have always said to try it as is, and then add friction modifier if needed. I think i've done 3 drail/refills with the Mobil and never needed to add it.

 

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AeroCoupe

lube between the nut and the face. I know my lubes

Founding Member

Oct 28, 2001

5,752

3,896

183

Claremore, OK

Feb 28, 2023

#5

• Feb 28, 2023

• #5

I use the Mobil 1 and modifier but I have the F150 “Z” spring so it puts a bit more pressure on the clutches and the modifier was recommended by others that have this setup.

Run it without as it’s easy to add.

 

WhiteCobra95

10 Year Member

May 2, 2006

626

171

74

Feb 28, 2023

#6

• Feb 28, 2023

• #6

Royal purple also says that friction modifier isn't necessary. I got that reply from their tech support when I emailed them about twelve years ago.