Can anyone help?

This is the second times, first time was 2k miles ago and I add one quart 'mobil one'. I checked the garage floor and nothing is leaking. Should I take it to the shop to check? or just keep adding another 'Mobil One'

Thanks

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00' CLK 430
Silver, K3, K4,Command
AMG Alum. Pedal
Momo "CF" Shift Knob
Lowenhart BR-5