I'll be changing my differential fluid tomorrow. The owner's manual says "Trac-Lock requires an additive." Any idea what this is referring to? Chrysler doesn't say in the manual. I've got the slippy diff in the rear. So apparently there's an extra small bottle of something that I need to add? And if so, how much? And do I subtract that amount from the oil I'm adding? Thanks in advance.

 

So you have a limited slip, yes? Then you need to add friction modifier to it to help the clutches slip when turning. However, MOST full synthetic gear lubes incorporate these additives already.

 

Correct, and thanks. I checked Mobil 1's website and you're right! Saved me money.

 

There ya go I run the Mobil 1 as well.

 

Simple question; simple answer.

I know people who just don't appreciate the value of a vehicle specific forum.

 

So would it be overkill to get the LSD additive from Mopar? I talked to a transmission shop who I've been going to for years and he said he would still put the LSD additive in it so it doesnt make sounds.

 

It also would be less effective when you actually want the limited slip to attempt to power both wheels. The friction modifier allows the clutches to slip when turning and not chatter, it's walking a light between traction to both wheels, and comfort of daily driving. The more you add, the less traction you could potentially have between both rear tires.

 

Summarizing this explanation: With synthetic lubes, don't add anything unless you suffer gear chatter. I've got lots of miles on Mobil 1 without the additive; you'll be fine.