you must not be from the rust belt . even a new vehicle with the best of care operating in this environment will rust out in a few years..
brake lines are a big problem. the rocker panels also.
road chemicals attack the finish and chrome / wheel parts..
10 years is very hard to do unless you do not drive this in the snow or when the roads are wet with de icing chemicals..
I do my own oil changes..this includes drive train fluids. I use the high quality oil filters and synthetic lubes. I don't trust any lube jocky..
I have been given free oil change coupons from the dealership many times , NO WAY !
with any leak the level will drop. with your 98 you should have dexcool in it... this would require replacing every 3-4 yrs and then mixing with distilled water. I use a 65% dexcool mix to 35 distilled water..I used the distilled water even with the silicates coolant in the 1983 vehicle ..never any leaks ...
If you have a intake manifold leak it will not take long to show..once the metal corrodes the gasket will push out...