It is hard to carry on a conversation in my 1984 300SD above 65 miles an hour on the expressway. Would silicone on the gaskets help or do you have any other suggestions?

 

What kind of noise, wind noise? Tire noise? engine? But from the little information I gather is that some seals are going bad and or are dried out. You are on the right track with the silicone. This most likely will fix the problem. And it's not hard or too expensive.

 

Thanks, It sounds like air noise around the back of the door at the top rear area of the window area. Is silicone for this purpose sold at auto parts stores? I just wondered if was a common problem. My wife and I have trouble hearing each other on road trips because the noise is so loud.

 

it is a common problem on older cars, especially the ones over the 20 year mark. You should be able to get it through the general auto part store easy.

 

I have the same problem with my 79 450SLC. All the weatherstripping around the windows need replacement. However I am doing them one at a time as the are very, very expensive. That is where wind noise usually comes from bad rubber or door panels not fitted properly, if replaced from accidents, rust, etc.