What can/will happen if there is no posi additive added to the rear end oil of a posi rear end?

 

According to the people that I talk to, the rear will make a little more noise.

 

Any permanent damage?

 

According to Auburn no damage will be done. But they use cone clutches, don't know if that matters but some other sources do not recommend running a posi with no additive for any length of time.

 

The additives are marketed as "friction modifiers". With this in mind, I have to believe that there will be quicker wear on the posi clutches without it. How much? I really don't know.

For the cone-type posis (like the 9-bolt), there is conflicting information from GM that the additive should NOT be used... Go figure.

 

You need a limited slip friction modifier in a clutch type posi unit. The frition modifer sticks in between the plates better. If you do not have any in your rear end it will make a noise called chatter, it will burn up the posi clutches in a short time if you drive real hard If you think you dont have it in your rear end take the fill plug our and stick your finger in the oil and smell it. Gear oil always semlls bad, but limited slip frition modifers are almost unbearable to smell. If you don't I would take the cover off and drain your rear end and get the right stuff.