I've seen some lint buildup even on my benz key... my W126 has a more fancy type of key then your standard car lock. I bet the lint on the key can build up in the lock cylinder too... never a bad idea to keep things clean.

-Jaosn

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.