I would suggest everyone keep a log. I use Excel, but you can buy log books or just a pencil and paper if you prefer.
In it you can keep a log of mileage, but much more than that. Including maintenance, repairs, improvements you've made. Also very important is part numbers for any parts you've bought. Sometimes a part that is easy to identify today, may be very difficult to figure out later.
Once you get started keeping a log you will find plenty of things to keep a record.
I even keep a record of the site numbers we've used, and notes about whether we would want that site, or a different one, next time.
