The ultimate biggest difference is doing regular oil changes on the car, that will keep the engine running great, as long as you don't run it to death.
Go ahead and do it around every 3K miles. It's an estimate, but a good one. If you go up to 5K, you might notice the engine doesn't run as well when oil is really dirty. Plus dirty oil means that---dirt in the oil, so that means contaminant, and it can scar the engine walls as the dirt circulates in the oil. Not easily, but over time.
I would suggest, with 100K on engine, to start using a synthetic oil, or synthetic blend. It helps engine to run sooo much smoother. I have a 1991 Geo Prizm (fake Corolla) with 240K miles on it, got it with 120K. And engine is cleaner and smoother than when I got it. I've used synthetic in it all this time. Might give you little better gas mileage, too.
Tires are highly important. Always keep good tires on car. Don't let them get bald. Tires are what keep your car on the road, what stop your car when braking. So make sure you have good tread. It also helps keep alignment better with good tread, because wheels aren't turning oddly, when the tires wear differently. So much easier to steer, too.
With an auto tranny, I'd change oil about every 50K miles. Some say let it go for 100K, but it gets dirty too, just not like motor oil. Some say to change it 20K, but it takes few thousand miles to condition the oil, to break it in. So 50K would be fine.
If it's a standard manual tranny, then do the same 50K miles. Just to be on safe side.
To change tranny fluid? Any of the name brand oil change outfits will do. They usually have motorized machines to change it, rather than just drain it out. They also have a $120 flush job which sucks everything out of tranny, even the little metal fillings which come off the metal parts and can mess stuff up if they stay inside the transmission.
I've gotten my motor oil changed at Walmart. They do good job. If you have a favorite place, then enjoy them. But check oil once weekly. Motor oil doesn't have to be up to top of dipstick. You'll see there's an area on dipstick that's okay for it to be in that range. But don't overfill.
Another important thing is to check tire pressure weekly or every other week. My best friend never checks his and has brand new mustang, and it's had tire pressures down to 15#!! Idiot!! He's ruining those $100 tires!! So even if it's just once a month, get a good tire gauge and check pressures. keep them around 32-35#. Higher pressure will ride better, but you'll feel bumps easier too.
Another thing most people don't realize is to change out radiator fluid every 2 years. Keeps radiator cleaned out too.
tune-ups, even an occasional bottle of injector cleaner will help to keep engine clean inside and out.
