I have been having "slips" into gear with a soft clunk or lurch. Do I need to replace the prop shaft on my 2012 Volvo xc90? Or maybe flush tranny fluid that is sealed for life? Or both? Does anyone have helpful videos on the replacement? I didn't find any really good ones on Youtube.

 

trannys are not sealed for life, its just that most manufacturers don't have a requirement to change fluid on the scheduled maintenance. Certainly you can check the level/color of the fluid or do a drain/fill through a filter to see if there's any debris that suggests internal damage. Drain/fill procedures vary by transmission. the 5 speeds are pretty straight forward if you simply want to freshen the fluid. drain 2 quarts into a measured pan, add 2 quarts then run the car to circulate. Rinse and repeat for about 4-6 times then check cold/warm levels via the dip stick following the factory procedure (which is a driving cycle to warm the transmission to check the warm level). This will get you back to a nice red/reddish brown color and ~80% fresh fluid. Plan B is to use a shop that will due a full flush. There they use other techniques like opening the lines to the transmission cooler and use that as an access to pump out the old and suck in the new. For the 6 speeds, the drain/fill is a bit more complex since the drain is a two stopper system. The inner plug drains overage down to the fill line, the outer plug removes the fill tube for a complete drain. To set the level, the transmission is filled to the approximate level then the car is warmed until the transmission is 55C (a shop will use VIDA to get this reading) then the inner drain is removed allowing any excess to drain - putting the fluid level exactly at the required fill line.

The other thing to do before the drain fill is to inspect and test the motor mounts and transmission mounts. You may be hearing the transmission or engine moving around due to a wonky mount.

PS yes there are vids on youtube:

 

Thank you so much for that info mt6127! I do not have a dipstick so I would have to do the inner and outer drain plug method. Thank you for the video as well!

 

which transmission do you have? on some models the dipstick is really hard to see as its way down there.. As noted the 6 speeds use a fill tube in the drain so those would not.

 

mt6127 I have the 2012 xc90 3.2L. It is a 6 cyl.