Mobil 1 Differential Fluid with additive?
Thread Starter
Race Director
Joined: Oct 2000
Posts: 16,477
Likes: 1
From: Enter Post Count Here
Mobil 1 Differential Fluid with additive?
I just changed my differential fluid, I had Mobil 1 in it, with a GM posi additive.
The additive came out looking crystal clean, the Mobil 1 looks dark, but still mostly good. Its been about 2 years since I changed it. The posi-additive and Mobil 1 don't seem to be compatible, they don't mix at all.
I put Mobil 1 back in, with 4 ounces of additive, because even if they aren't mixing, the last 2 years with this concoction didn't look burned and was still very viscous between my fingers.
The Mobil 1 didn't say anything about needing or not needing a posi additive, the maintenance manual says to add it, so I did, just to be safe.
The posi and rearend are working great, but it'd be nice to know what is the best fluid setup to run.
Thanks.
The additive came out looking crystal clean, the Mobil 1 looks dark, but still mostly good. Its been about 2 years since I changed it. The posi-additive and Mobil 1 don't seem to be compatible, they don't mix at all.
I put Mobil 1 back in, with 4 ounces of additive, because even if they aren't mixing, the last 2 years with this concoction didn't look burned and was still very viscous between my fingers.
The Mobil 1 didn't say anything about needing or not needing a posi additive, the maintenance manual says to add it, so I did, just to be safe.
The posi and rearend are working great, but it'd be nice to know what is the best fluid setup to run.
Thanks.
Pro
Joined: Dec 2000
Posts: 700
Likes: 20
From: Derby Kansas
Re: Mobil 1 Differential Fluid with additive? (NoWorries)
I used Mobil 1 with GM posi additive in my 95 Z28 and currently in my 78 Z28 and 85 Corvette with no problems.
I'm thinking they may seperate after sitting for a while, but once everything starts turning inside the differential they'll blend back together.
[Modified by Ron78Z&85Vette, 1:26 AM 10/5/2002]
I'm thinking they may seperate after sitting for a while, but once everything starts turning inside the differential they'll blend back together.
[Modified by Ron78Z&85Vette, 1:26 AM 10/5/2002]
Drifting
Joined: Apr 2000
Posts: 1,803
Likes: 1
From: PA
Re: Mobil 1 Differential Fluid with additive? (Ron78Z&85Vette)
The additive reduces clutch stiction and posi breakaway torque. This means the posi clutches break loose quicker and easier. The result is less creaking and clicking noises during maneuvers at full steering lock. This is what's important to the average consumer because they thing something is "wrong" if they hear a noise. Such consumer complaints drive the OEM's nuts (broke) during the warranty period. More significantly (for me), the additive causes your posi to break loose sooner (easier) and it will smoke one wheel instead of transferring weight and accelerating. I...for one NEVER use posi elixor in my vehicles. My RWD minivan will never see it and especially not my sports car. My Dana 44 C4 with Mobil 1 makes very slight noise when cold with no additive (at full steering lock). Results will vary due to posi wear, varnish, age and gear lube type.
[Modified by Rick93Z07, 1:22 PM 10/5/2002]
[Modified by Rick93Z07, 1:22 PM 10/5/2002]
