My creaky doors were driving me crazy, enough to think about trading in my Countryman but I finally found a solution to the creaky door seals from the body flexing going over bumps or into driveways. After exhaustive research I found that I needed some kind of Teflon lube... Stay away from silicone, it makes it worse!! I found CRC Dry Lube with PTFE (Teflon). The great thing about this is it's safe for rubber, it penetrates the seals, it's dry, and it repeals water and dirt. I sprayed this stuff on a rag and coated the door seals, the rubber on the top door frames and along the area where the door meets the rubber seal. It's been three weeks and still nice and quiet. You can find it at Home Depot, online, or any hardware store. The whole car just seems more solid without the creaky doors. Silence at last!!

 

This stuff is amazing, now I used it on some door panels like the piano trim. I had one that would buzz on the back doors so I sprayed all around the trim and wiped off the residue and no more buzzing. It goes on dry and not greasy.

 

It's also great on Ritz Crackers!

I've always used "Gummi Pflege Stift" on BMW's as it seems to be the thing to do. But your method is probably easier. Going to try it next time.

 

Seems to do that same thing, the doors seal better, less wind noise. Not sure what the longterm effects on the rubber are are but it says it's safe on rubber and plastic and I haven't seen any harmful effects. Try it