I have a 1992 Buick Regal with the 3.0 V6. My wife put the first 60,000 on it, I put the last 140,000.
Oil Changes: 5-10,000 whenever I remember. I’m not a fanatic.
Oil: Whatever the shop uses for that make of car. 10W30 or 5W30, I’m not sure.
Gas: 87 octane.
Service manual: Never looked. Just kept my eyes and ears tuned to running condition.
Trip mileage: used to be 90 miles/day. Did that for at least 3 years. Almost all driving was long distance.
Driver’s attitude: on the aggressive side. I like to drive over the speed limit. 10 mph over or more.
Never warmed up the car. My wife did. I just drove a little more slowly when it was real cold until it warmed up. And it was usually in a garage.
I attribute the longevity to: a 6 cylinder engine. Always keeping oil in it. I don’t think it is necessarily the amount of changes, but NEVER let it run low on oil. I learned that lesson with 1983 5.0 Mustang. BAD BAD BAD.
I have had very little maintenance on the car. Almost none to the engine. Only when needed. I keep a pretty good eye on the oil level and serpentine belt condition.
I have had very little problems with this car.
I gave the Buick to the kid. But I would not let him drive it long distances on the outside chance that things will start to go out and he will be stuck somewhere. He just drives around town.
Now let me tell you about my 1983 Mustang. Being the stupid kid I was then, I let it run low on oil. I have heard that the 5.0 engine for 1983 had problems. Be that as it may, you will have problems if you let the oil light tell you you need oil. By then it is too late.
Live and learn.
Oh by the way, my '97 Pontiac Grand Prix (3.8 V6)has 200,000 miles on it. I bought it a year ago and only put 10,000 miles on it last year. I think it has a few good years left.