Haldex and Rear End fluid question

[tjmotter]

I have read multiple threads about changing the fluids in the back of the XC90 but am confused about 1 discrepancy:

All of the posted tutorials on this end with the tech adding fluid and putting the plug back in but I have seen several video's that end with the tech removing some of the fluid. The amount seems to vary between 40ml's and 60ml's but I can't find a definitive description for this.

First, is it necessary to remove some fluid?
Second, if so, how much for the Haldex and how much for the Diff?
Third, any idea why anyone would design for this? I have worked on many different brands and this is the first time I have seen a requirement to remove fluid. In every other instance you simply fill until the fluid starts to come out and then put the plug in.

thx
Todd

[SuperHerman]

Good questions - unfortunately I don't have VIDA any longer, but I am sure someone with it will update. I assume this is for the 2008 XC90 you have listed.

Here is what I understand on the Haldex - because one doesn't know exactly how much is actually sucked out an exact amount cannot be replaced for two reasons: 1) Fluid not sucked out; and 2) fluid that is in the filter and drips out.

From my recollection once the system is full, dripping over the edge, and the filter has been filled, driving around, the correct amount is 100ml under the fill plug. This is what I recall on my old V50 awd - your XC90 may differ.

So by filling it to the drain plug, with a dry filter and then driving the car for a short period the system is ready to be zeroed out. Add X quantity of fluid to get to the fill plug - zeroed out, and then removing 100ml to get it to the proper level.

Two things - 1) the 100ml is what I recall - verify. 2) The car must be level.

I suppose if one has done enough of these - they may learn that the filter absorbs 50ml so experience tells them to remove 40ml. They also know how to fully evacuate the system. Without this experience based knowledge and expertise - the VIDA instructions for year and model would be what I would follow.

On the diff I just fill to the plug - haven't had an issue yet - but my fill numbers are consistent with what has been removed and what the data sheet says the system needs. There is no filter so it is more exact.

[tjmotter]

Closing the loop: Installed VIDA and the correct amount to remove is 40ml in a 2008 XC90 V8. Differential should be filled until it starts to drip out (nothing removed).

thx
Todd