My FSS is showing a wrench symbol along with "30 d" which I know means 30 days until I need to change the oil. It was showing miles until recently. My question to you all is does the FSS automatically switch from miles left to days left or did I inadvertantly do something that caused it to display days instead of miles. I would prefer to see miles left instead of days. I bought the vehicle used and was not fortunate enough to get an owner's manual with it. I've also used the search function on the forum and was not able to find the answer. Any help would truly be appreciated.

Thanks!

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-98 Polar white ML320 - M1 Package, Bilstein Shocks, H&R Rear Lowering springs, monochrome paint scheme (like MY2000+ ML's), ML430 wheels and tires, MY2002+ halogen headlights