ZAK Differential Oil Additive?

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Mar 11, 2023
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15
Location
West Phoenix, AZ
Has anyone had any experience with ZAK Differential Oil Additive? Or even heard of it?

A few months ago, the dealer (that used to be good) changed the oil in both differentials on my Outback and supposedly added some of this ZAK Differential Oil. I've gotten used to the idea that it is in there. But I'm hoping that it doesn't cause any damage.

ZAK is supposedly a Berkshire-Hathaway company, so not good news there. But it is also supposed to be a limited slip additive, and neither of the Subie's diffs are limited slip.

Any thoughts? And thanks.
 
Well if NO limited slip clutches it's not going to do anything. I don't see how it could improve the performance of any gear oil.
 
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Has anyone had any experience with ZAK Differential Oil Additive? Or even heard of it?

A few months ago, the dealer (that used to be good) changed the oil in both differentials on my Outback and supposedly added some of this ZAK Differential Oil. I've gotten used to the idea that it is in there. But I'm hoping that it doesn't cause any damage.

ZAK is supposedly a Berkshire-Hathaway company, so not good news there. But it is also supposed to be a limited slip additive, and neither of the Subie's diffs are limited slip.

Any thoughts? And thanks.
When bringing any vehicle to the dealership for service , I give them a printed sheet stating the exact service I want them to perform and that sheet is attached to the service order documents.

On that sheet it states no third-party or OTS additives shall be added to any lubricant.

The main question one should always ask about any third-party or OTS additive is this: "What chemistry from a third-party or OTS additive is being added to the formulated lubricant that it does not already contain?"

I have never received a qualified, logical answer to that question.
 
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