Had it on both on my 2007 -- Coupe and 2005 -- Roadster. I have not seen this on the forum but perhaps this should be a timed replacement like air filters. Some will say if it is not broke; don't fix it. I have noted two distinct symptoms on my cars. One is the leak and the other is the smell. I found the leak when it was just seep and not a leak. I found the smell when it had gone to a leak. I guess you could get a combo of the two. Many people do not look under the lid often enough.