My car is 94 Civic with 187K miles. The engine + tranny + suspension rides like new. So as long as you give good maintenance, you can easily take cars past 100K.
The three most important liquids are engine oil, tranny oil, and coolant. They exist solely for the purpose of protecting the car (engine and tranny). Other parts can wait till they fail (of course the timing belts need PREVENTIVE maintenance also).
The key is to use synthetic oil in the engine and change it every 8 thousand miles or so. Also to do engine coolant flushes at least every 3 years. Then the engine should easily go double the life of an automatic transmission which will give out before 200,000 miles even with transmission flushes every 50,000 miles. Hopefully your engine has a timing chain rather than a timing belt. If it's a belt and you have an "interference" engine, make sure to change the timing belt per manufacturer maintenance schedule.
I would not recommend using synthetic oil on an engine with that many miles on it. You're wasting your money.
The secret is frequent, regular oil changes with decent quality brand oil, and prompt attention to the little things that come up before they become big things.
Every car I've had for the last 20 years has gotten 150K minimum. I had a Honda that went 288K before the timing belt broke unexpectedly. You should get another 100K at least out of your car if you just give it normal expected maintenance. Long distance driving is better for the engine than stop/go.