Does anybody know the size of the engine oil drain plug on 94 C280? My last oil change was done by a dealer for $20 when they had promotion. Apparently they torqued the drain plug too tight. (Don't all the dealers change oil by sucking oil out from dipstick tube?) I swear I will never let others change oil for me again, no matter how much saving I get. Anyway, I need a new drain plug. Just went to a local auto part store and they have M14*15. I believe it means 14 mm in diameter and 15 mm in length. But I remember I used 13 mm wrench to loose the drain plug. Any idea?

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Harry (94 C280)