Not sure if my first reply went through so I will try again. I have a 2003 SC 430 (now about 119,000 miles) that I purchased used (with about 20,000 miles) in 2006. I have used GM Silicone Grease, Part #10131290, which is designed for lubricating weather stripping. I have lubricated all of my weather stripping (including the weather stripping around the convertible hardtop) 3 times, last time in 2017, and all of my weather stripping (original) is in excellent condition. I live in the Chicago metro area, keep it in the garage, and I do not drive it from mid December through April.
