I write all my info in a small notebook I keep in the car for everything I service. In other words, dont rely on computers 😉
I read the owners manual. It says to take a pic of the receipt and mileage together. This is to help with warranty coverage.I am a5k guy for decades. Easy to keep up with and don't have to do any figuring. Save the receipts for the oil changes in your owners manual and no need for a spredsheet or anything difficult and time consuming (Thi incluses all maintenance and repairs.