I have had two instances of low tire pressure warning light coming on, both when in colder weather than normal on a trip. One on 2005 SL500, one on 2007 SL550. Anyone have experience with putting nitrogen in the tires?Results? Cost? Thanks!

 

Virtually every tire on the planet slowly loses air. As the air temp drops in the winter, the air inside the tire shrinks and takes up less volume. All of my cars need air in the fall as winter approaches. Both your situations indicate cooler temps in your trips.
I always put air in my tires prior to a long trip because the car is usually fully loaded and a fully loaded car needs more air in its tires. I suppose even an SL needs more air if you load up the trunk and rear seat area.
As for the nitrogen question, I have no idea. My understanding is that nitrogen does not retain moisture and will prevent inner wheel corrosion but the seal between the rim and the rubber is the same so I doubt the nitrogen would stay in the tire any better than plain old air. If the nitrogen does NOT expand and contract as much as air, I suppose it may solve your problem.
I also believe the tires may run cooler with nitrogen.
Is the cost worth it? Only you can judge. Suffice it to say that the cost will be higher than good old air.
Good car maintenance dictates that you check your tire air pressure once a month anyway. I usually check mine when I need windshield washer.

 

I agree with everything that gilgorm said above.

Nitrogen will not make any difference on your slow leaking problem.

 

OK, thanks for your input. I'll forget about the nitrogen and focus on more frequent checking of tire pressure, especially before a trip!