Many of these tips apply to all cars, some to these cars specifically:
-NEVER LET YOUR CAR OVERHEAT!!! This seems to be the death of the 2.5 and 2.8 motors. Blown head gaskets often result. If you do not have a temperature gauge, and only an idiot light, it is often already too late by the time the light comes on (at 260 degrees). If the light comes on- STOP IMMEDIATELY - though it already may be too late. Even if you have not blown the head gasket, persistent oil leaks often result after overheating
Check your coolant level often, and change it every 2 years.
If the level gets low, the car may overheat and you may never know because there is no coolant passing by the switch to turn on the HOT light for you. This is a great way to destroy the rings in the engine, too.
Also, check to make sure the cooling fan comes on in traffic, or when the air conditioning is turned on! If not, get it fixed immediately! Personally I like to bypass the fan switch and have installed by own toggle switch underneath the dash- which I turn on whenever the temp gauge starts to rise; or if not on a gauged car, whenever I get stuck in traffic. You can get a lighted toggle switch so you'll remember the fan is on.
Be forewarned. My friend's 81 Omega V6 died because she a.) overheated the engine which b.)blew the head gasket & she didn't know until the car started backfiring. But then even when she DID know there was a problem she kept driving. Coolant mixed with the oil, diluting it and within 800 miles she had ruined the engine because the bearings didn't get lubed enough.
Another friend's fan switch stopped working on an 85 Skylark V6 so the car overheated after being stuck in traffic for 20 minutes. Luckily she stopped immediately.
Our family mechanic tells me that overheating followed by the head gasket blowing is a common death for 2.5's also- we never did this to our car which is why it is still around.
I think that this is one reason why there seems to be fewer X cars around than A or B cars from the same vintage- these rear wheel drive cars had engine driven fans instead of electric cooling fans whose switches can stop working - also the cooling fan switch on the X cars waits until the car gets too hot before turning on.(i.e. 230-238 degrees). I think with an engine driven fan you are less likely to have the car overheat on you unless you lose all the coolant in the engine due to a leak or something.
-Keep your oil changed!!!!! If you do nothing else to take care of your car, do this! Every 3 months, or 3000 miles change your oil AND filter! And check the engine oil level often. I like to be extra careful and change my oil every 2500 miles. 10W-40 should be the oil used if the car has over 75,000 miles on it. If less, you could also use 10W-30. Also use 10W-30 in cold climates. Use 10W-40 in very hot weather. DON'T use 20W-50 unless your bearings are shot & you're getting the oil light on at idle.
-Change your transmission fluid every year or 15,000 miles- this will help promote its long life. Check the fluid level and its condition often. If you drive up hills a lot or live in the mountains, make sure the fluid isn't turning brown.
-Change your brake fluid every 2 years- this will help prevent a host of annoying brake problems, such as stuck wheel calipers and deteriorating wheel cylinders, which can occur if you leave the fluid in there and let it get oxidized (dark red instead of clear).
-Don't use crappy gas- stick with one brand to help prevent gumming in the carburetor. Also replace your fuel filter every 2 years or at each tune up.
-Tune up the ignition system (check timing and spark plugs, spark plug gaps, distributor cap and wires) yearly. Replace the spark plugs every 2 years or 20,000 to 25,000 miles.
-Wash and wax your car often, particularly if it sits outdoors all the time. If the rain doesn't bead on the surface, it is time for a waxing. My paint is so bad now, though, that I stopped. You can overwax, and the excess gets stuck in the paint's spiderweb cracks. It looks bad.
-Don't neglect maintenance and repairs! If you know something's wrong, don't put it off!