Originally Posted by cudaspaz

I've done tons of those O-ring repairs at the dealership, as it is a very common problem.

Not fun to get the bolts lined up going back in, but take your time and you should be fine, but you should run the car and turn the wheel stop to stop and keep checking your fluid until you get it topped off right.

Sometimes it takes quite a few miles to get all the air out of the system, but get the level good with no foam first in your driveway.

Some vehicles require that you drop the rack down for clearance to get the bolts out to replace those O-rings, and I can't remember if your 420 has enough clearance to do it.

I would get the O-rings from the dealership since they are familiar with the problem.