You learn.
It isn't THAT hard if you put your mind to it. In fact, today's cars (if you're lucky enough to have a newer one) are so smart that they'll TELL you when your water or your oil is low.
For older cars, get a friend / neighbor / spouse / smart teenager to show you where and how to check fluids, belts, tires, etc.
God forbid there comes a day when you're out driving somewhere, somewhere a bit remote, and you get a flat tire. Your cell phone gets no reception.
*imitating Karl Malden*
What will you do? What WILL you do?
Or, you go to your friendly local oil change place for the first time and ask them if your oil needs to be changed. The young buck on duty, still in high school, finds the oil dipstick, pulls it out and shows you - "Look, it's dirty - you need a full oil and filter change".
Problem is, the oil SHOULD be dirty, to a degree. It's doing its job. You need to learn to go by your car manufacturers recommendation as to when you change your oil. It used to be every 3,000 miles. Now, depending on the car and what TYPE of oil (something else you can learn), you might go 10-12,000 miles before you need to change it.
As seniors, it gets a bit more difficult to change a tire - I understand that. But at least then learn the going rate for tow truck service in your area so you don't get ripped off.