XFires also have a steering damper on the front suspension. It's really just a cheap shock absorber, costing about $15-$20 depending on your supplier (lots of available sources for this part throughout internet). I consider it essentially the same as any other routine maintenance item, like changing the oil. In fact for me, an oil change is about every 2 years and I typically replace this steering damper also. I'm under the car's front end draining oil and might as well replace the steering damper.

I've attached a reference document that covers recommended oil for the M-B sourced engine. Most folks use the fleece filter ($10-$11), but those that use the paper filter (less costly) also get good results.

Again, Enjoy