Looking at purchasing an 89 firebird formula. I'm not familiar with these cars, but I am a huge fan of their look. My question for those of you that know these vehicles/engines a bit better is as follows: Suppose it has been decently maintenanced/taken care of. How much life can I expect to get from the L98 in the formula with 151k on it?

Well, there are people who have had them hit 200k+ then there are people like me where mine went at 68k... It all depends...

I would check it out. If it runs good, no smoke, or funny sounds, then I wouldn't be too worried about it.

I'm not so sure about the 350 but my 5.0 is going on 180,000 at its still running good. Only thing thats been wrong with it is the normal things for a 25 year old car. needed shock, struts, rotors(all replaced by the po)some break line, and i just replaced the radiator a few days ago. As long as the pedal wasnt mashed on every straight away and oil changed regularly it should be ok for now. Like bullydawg said, its it runs ok and you don't get any bad signals(smoke etc.) i wouldn't really worry about it.

I have a 89 350 Formula that is about to hit 160k. I know its only 10k difference, but she seems to have plenty of life left. Like what was said above just the normal wear and tear things are what I have had to deal with. (Rotors, Struts, Brake lines, Water pump, Radiator)

I've got 89 formula that has around 184,000mi. Its all stock and haven't had any major problems. I've only had to change the fuel pump, alternator, smog pump, starter.

151k miles can mean a whole range of different things depending on the previous owners. If it was well maintained and/or highway driven, it's nothing to worry about but if it has been poorly maintained and had the piss driven out of it, it could be very rough at 151k.

The engines themselves are pretty bulletproof and can put up with some real tough times. If it hasnt been abused, itll probably just smoke on start up like most of them do but itll keep running long enough for you to have to worry more about the car around it than the engine itself.

Well again as many others have said the overall life span of the car varies greatly with how it was maintained. So to try and put a guess on it just wouldn't be possible with any kind of real accuracy. The best answer i can give is at 150k i wouldnt EXPECT a whole lot of life left in it granted there are many of these cars that can easily get up to 180k -200k even in some cases 300-400k when well maintained but without knowing the history or current condition of the motor i would expect the worst and hope for the best. If you wanted a good approximation of what kind of shape the motor is in to figure out how much life is left get a compression or leak down test done check the oil pressure check the engine vacuum. Also its not just about the motors there's the transmission to contend with as well. Typically theres very few people who change there transmission fluid even though it should be changed so i would at least check the condition of the transmission fluid if its not nice and red expect to have to do a transmission in the near future. Again its hard to say what will be needed thats why its good to expect the worst and figure out if its worth it to you to fix it. If the cars cheap enough you could easily justify a $1500 motor rebuild and a $1000 transmission rebuild and virtually have a new car.