Seriously? 10k and you never lifted the hood even once? My oil gets changed every 3000 miles (even running full synthetic) and I have the hood up every weekend doing something (cleaning, adding something, whatever) so it's just common practice to check the oil.
And just an FYI, but if any of your cars are using oil, you need to get it looked at. My car has 32000 miles, gets driven hard regularly, and doesn't use a drop between changes.
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