Well I was driving today and watched my odometer roll over 172,000 and it made me wonder how much life I should still expect out of this tired old motor. I'm very sure it's still the original and it still runs perfectly fine, holds oil pressure, and doesn't burn anything.
I know proper maintenance should keep it good but obviously it can't last forever, so what do you all think, how long do they usually last before they decide to kick the bucket?

 

my odometer stopped at 186,xxx over a year ago and its still running great. i guess its just a matter of how well the car was taken care of. proper oil changes etc.

 

They will run forever if maintained. If not, when something breaks, you fix it and keep driving.

 

My 94 chevy c1500 truck is at 200,000 and runes great for the miles on it. I hope that the engine going into my 85 Z28 last half that.

 

my friends 86 monte ss with a 305 H.O. had 300,000 plus on it when he got it off his gran father he killed it in a year or so. It all depends on how you drive and how well you maintain it.

 

314 000 km and still going

 

my bird hemorrhaged at around 90K miles... I had it for about 10K or so ... about 5 years... when the engine was disassembled, pistons were cracked and walls were scuffed, had to go .040 over... I think that was the correct measurement...

 

Of course it's possible you could throw a rod or have a valve break, etc. but those things are rare. Otherwise, I go with the "forever" answer. I had 426,000 miles on my 85 caprice 305 chevy engine, with no internal engine problems, when I traded it in last year. But I kept VG care of it.............

 

Yeah I understand they'll last a while if you maintain them and replace stuff when it breaks. What I kind of meant more was how long until a big mechanical failure like a thrown rod or what have you.

 

I purchased my son's 1992 Firebird with the TBI 305 new. I drove it pretty aggressively for years and years, racking up 193,000. My son and I re-did the whole car including stripping the engine down to the bare block and heads. It was rebuilt as a learning point for my son, plus to get some "skin in the game" so he took care of it.

When we pulled the engine apart, I knew it didn't need to be rebuilt. I was religious about all maintenance, but particularly oil changes every 3k with a good quality oil and filter.

 

Drain the oil and coolant. Run the engine at WOT, and you can expect anywhere between 30 seconds and 15 minutes.

 

Cliff Jones on GTASource page got 305,000 on the 5.7. died the other week. he kept it up too.

 

frequent oil changes at appropriate intervals and maintaining the air/fuel system will prolong the life of your engine as well as your heads...

 

Almost 210K on mine, still going strong. I've been driving the **** out of it for over 10 years. I also have been using Royal Purple and Redline since only 70K miles and NEVER go more than 5K on an oil change. I also think I've replaced every sensor on it ATLEAST once as a preventitive measure. It has NEVER left me stranded.

Now my transmission, I just started on my 3rd. they only last me about 100K exactly.

 

That thing was raced hard, too. Even had a small cam in it.

 

mine has a little over 190,000 mi. im almost 100% sure its the original engine, suprisingly my car has literally no rust, and im in the midwest. but the engine has most likly been rebuilt idk when, but right now it has been running great exept the water pump just went out and when i took that out i fugured id take a look at the timing chain and omg! it has over an inch of side to side slop so im replacing that but exept for the water pump it seemed to be running fine. the owner/s who had it before me probly drove it fairly hard to.

 

Graph. I've heard of fatal things happening to V8 engines like sucking a valve, pistons cracking, rings breaking, rods being thrown, and they happen even under 100,000 miles. But I must say I've never met anyone who actually had it happen, so it must be very rare.

 

Seems to me like piston ring wear and bore wear inducing excess blowby is what kills most engines. If the constant burning of oil doesnt start to mess with things mechanically, the eventual point where the owner will not keep putting enough oil in it and it runs dry will kill it.

I kind of always had the impression that v8s that didnt blow up from racing and constant high RPMs usually succumb to oil starvation because blowby uses up the oil in the crankcase before the owner can refill it.

I'd call an engine living on borrowed time past 200-250k miles. I think they could go much farther if maintained, but I think once you hit 175k or so, poor maintenance will start to catch up with it and proper maintenance will ensure it will last to 250-300k miles.

 

For your info; I just heard on the radio of a 2006 ford truck with a million miles on it? Now the motor was replaced at 190,000mi. But we were figuring the guy had to average over 690mi. everyday 365 days a year. Doesn't seem possible. BTW, he delivered greyhound dogs i guess.

 

If you were to ask me, I would say those were mostly highway miles, which are miles that don't impact the engine as much as stop n'go miles... or so I think...

 

I have 148,000 miles on my 92 RS, and it seems to run like new. No oil burning, no blow by, no nothing. I am fairly easy on it, and I change the oil every 3000. I use snake oil in my Camaros also. I add marvels mystery oil every time I gas up, and I add STP to the oil at every oil change.

 

The V6's will run forever if maintained too. My 2.8 has 294,000 on it. But it was regularly maintained it's whole life, I've got records back to 1985.

 

291,000 and counting on a 305 TPI. Oil change every 4K with Penzoil high mileage brand. Filter change every 8K. While most of it is highway miles, the engine has been abused. I have a trailer hitch and recently pulled 2000 lbs of stuff up and down the east coast, driving for 6 hours straight and engine temp at around 210 degrees. BTW - having a 5-spd is great for the motor (you can let 'er coast going down big hills). Am on 3rd clutch (but they were replaced without them being worn out). Car still passes emissions - only if I run the motor hot. I do have to add 1 quart in between oil changes.

Now the car has stranded me a few times, I've had the electronic module in the distributor crap out on super hot days (so I always keep a ECM chip handy in the trunk). On a rare occaission car wont start (I keep a can of starting spray too handy) - OR - the starter does not kick in when its all very hot (so it may need to be push started) - so I try to ensure engine temp stays below 210 by wiring the fans to a switch in the dashboard. But these are all rare.

Compared to my '78 Firebird, this '89 Iroc is 10 times better. While I love the way the older car looked, those 70's were built like crap. The suspension was crap. Only came with a 4-spd (no overdrive - very bad!), car rusted out like you would not believe especially the parking brake. The 4speed clutch Z-bar linkage broke on me once, I had to pull the engine out to fix it. Lastly, I had 3 engines in that car. It got shitty mileage with the Rochester 4-bbl. Plus, the '78 car is relatively dangerous, I've spun out more than once. The trunk on those cars were useless and tiny, If I drove with a "real spare" you could barely fit anything else it. Doors were too heavy too. Hatchback is much more practical.
Anyway, rust finally killed it, which was probably a blessing in disguise.

Long live the 3rd Gen's! Now if only they put in a glove compartment on the passenger side.

 

i assume all these high mileage engines have had the valve seals changed.

 

Nope, although since I burn at least a quart of oil in between changes, its either the rings or the valve seals that could be the cause of that. BTW - my mileage is about 27 MPG for highway. Is that good or bad? Anyone doing better? I noticed MPG was lower during some brutally cold winter weeks too, for awhile I got worried, but then that maybe normal in cold (0-10 degrees) temps?

BTW - Do have a small problem - in the summer, when the engine is cold, car acts like its running too lean and has no power. Its like its not getting the rich mixture it needs. In the winter this did not happen. Am guessing its the temp sensor in the manifold, but I've changed it at least once and definitely did some tests with an ohmmetter, maybe I should not use auto-zone sensors? Any ideas? Could be EGR valve related or a vacuum leak? When car warms up, idles and drives fine.

 

Think I had 224k on my 88 Iroc-Z before I stripped it. Besides the startup puff when it was cold it ran awesome! Car rotted away :/

 

Had a 91z28 Lb9 thats still on the road with well in excess of 300k. And i used to race it often. PENZOIL SYNTHETIC OIL!

 

How well do you maintain it? how well did the PO(s) maintain it?

Some people swear by synthetics, but the truth is a good maintenance routine will keep it in top shape more than what brand of product you use.

if synthetics or a supplement give you good results.. then by all means do what works for you. When I drove in excess of 30,000 miles / yr I used Lucas oil additive since it was all highway driving I changed the oil every 5,000 miles.

My truck had over 170,000 miles ran & looked like new when I traded it in.

 

My Formula was over 200K miles when I sold it. Still started right up, and ran great. Original engine and trans. I used regular ol' dino oil, changed at 3-4K mile intervals. It would smoke a bit first start of the day, but, that was it. Oil consumption between changes was less than half a quart.

 

The life of a motor is all how its driven and taken car of, Most of the time 305 / 350's fail because someone ran them hot until they locked up. I have never seen a broken rod on anything other than a race motor.

When you start getting high miles, Putting a High flow oil pump in is always a good way to extend the life. Also gives you a chance to clean up all the gunk in the bottom of you motor

 

if you dont beat on em by power braking popping the clutch at high rpm racing it etc and do proper maintenence the gm v6 v8 engines last damn near forever.

its usually everything else thats attached to the motor that gives you issues