3 ms·

Driving a vehicle with a cold engine (without a warm up idling period) will eventually destroy the engine.

ehnto 5y ago
That's not really true for modern vehicles. They handle it a lot better. Many are also designed to turn on and off constantly at stop lights, so they're designed to properly handle temperature and lubrication during the start/stop cycles. If you're in a particularly cold winter you might benefit from it but really that's a judgement call. If you live somewhere mostly above freezing and drive a modern car, you're probably good to drive from the moment you start the car. Unless you're about to go full throttle on a racetrack, should be fine. I warm up my 96 Nissan before driving, but I just go easy for the first 5 minutes in the 2010 Nissan.
- paulmd 5y ago
  > Many are also designed to turn on and off constantly at stop lights, so they're designed to properly handle temperature and lubrication during the start/stop cycles. Many late 00's engines were also designed to turn off cylinders to improve engine efficiency, but that turned out not to be implemented very well and engines died from carbon fouling. Big problem with Honda in particular iirc, and people would routinely bypass it to save their engines. Automakers have to comply with CAFE standards and other mandates, but at the end of the day there's no mandate that an engine made with gen-1 technologies will make it to 300k miles either. Automakers don't really care if your engine dies in 10 years or not, they've put out lemons before and they will do it again. Early CVTs failed at extremely high rates/short lifetimes, for example, and early OAT coolants like Dexcool were notorious for eating up every seal inside an engine. Early high-compression diesels had about a decade of their fuel injectors being eaten away by the abrasive sulfur before the ultra-low-sulfur highway diesel changeover. These technologies are of course completely normalized and trustworthy today, but that's not much consolation if you're the one paying the repair bills on a gen-1 lemon. For some reason "don't upgrade to a v0.0 release of a new major version of iOS" is common knowledge here but nobody wants to apply that same logic to cars. The general public gets it though. Now that cars have got 10 years of stop-n-start under their belt it's probably more reliable but still, it's a challenging design criteria for an engine. Not saying diesel fumes aren't a problem either, mind... we probably need to go electric in the long run. But at the same time, on the level of personal self-interest... it's probably better for your engine to not start and stop constantly. It's just bad when everyone is idling because they don't want to start and stop. Tragedy of the commons.
  - deleted 5y ago
    [deleted]
Wistar 5y ago
I don't think that is true except, perhaps in the case of much older vehicles—particularly carbureted, rather than injected—vehicles. Most of the advice I have read in, say, the last 20 years for gasoline-powered vehicles, is to allow no more than about 30 seconds to a minute of standing warm up before gently driving off. The engine will be fully lubricated within 10-15 seconds and ready to go.
- ashwagary 5y ago
  >allow no more than about 30 seconds to a minute of standing This heavily depends on the temp range you are discussing. Lubrication is the least of your worries at certain temperatures. The engine block and pistons being too cold cause problematic expansion and contraction which can lead to block cracks or permanent engine knock issues from what I've seen. This will eventually lead to needing an engine replacement.
  - londons_explore 5y ago
    But if driven hard while cold, it will warm up faster, reducing the damage that can be done. It's a trade-off, and nobody seems to have done the science properly - it's just mechanics and engineers guessing which effect is worse.
    - ashwagary 5y ago
      >But if driven hard while cold, it will warm up faster, reducing the damage that can be done. Is this sarcasm? I can't tell because it is literally the opposite of the truth.
- ehnto 5y ago
  You can actually hear my '96 motor quiet down as the oil makes it's way through the head. Takes about 15 seconds. I wait for the engine coolant temp to reach 75c before I give it a good wick. It fluctuates between 75c and 85c under good load. Interesting to me, is that when idling down a hill it does not drop, but if left in gear going down a hill it does drop in temp. It can actually get itself below operating temperature in gear going down a hill. I presume because the heat being pulled out via pumping air through the combustion chamber is greater than the thermostat would allow to be pulled out via the radiator.
dalkvist 5y ago
Witch is why you have an electric engine heater in cold(er) places, no need to idle :shrug:

That's not really true for modern vehicles. They handle it a lot better. Many are also designed to turn on and off constantly at stop lights, so they're designed to properly handle temperature and lubrication during the start/stop cycles. If you're in a particularly cold winter you might benefit from it but really that's a judgement call. If you live somewhere mostly above freezing and drive a modern car, you're probably good to drive from the moment you start the car. Unless you're about to go full throttle on a racetrack, should be fine. I warm up my 96 Nissan before driving, but I just go easy for the first 5 minutes in the 2010 Nissan.

paulmd 5y ago
> Many are also designed to turn on and off constantly at stop lights, so they're designed to properly handle temperature and lubrication during the start/stop cycles. Many late 00's engines were also designed to turn off cylinders to improve engine efficiency, but that turned out not to be implemented very well and engines died from carbon fouling. Big problem with Honda in particular iirc, and people would routinely bypass it to save their engines. Automakers have to comply with CAFE standards and other mandates, but at the end of the day there's no mandate that an engine made with gen-1 technologies will make it to 300k miles either. Automakers don't really care if your engine dies in 10 years or not, they've put out lemons before and they will do it again. Early CVTs failed at extremely high rates/short lifetimes, for example, and early OAT coolants like Dexcool were notorious for eating up every seal inside an engine. Early high-compression diesels had about a decade of their fuel injectors being eaten away by the abrasive sulfur before the ultra-low-sulfur highway diesel changeover. These technologies are of course completely normalized and trustworthy today, but that's not much consolation if you're the one paying the repair bills on a gen-1 lemon. For some reason "don't upgrade to a v0.0 release of a new major version of iOS" is common knowledge here but nobody wants to apply that same logic to cars. The general public gets it though. Now that cars have got 10 years of stop-n-start under their belt it's probably more reliable but still, it's a challenging design criteria for an engine. Not saying diesel fumes aren't a problem either, mind... we probably need to go electric in the long run. But at the same time, on the level of personal self-interest... it's probably better for your engine to not start and stop constantly. It's just bad when everyone is idling because they don't want to start and stop. Tragedy of the commons.
- deleted 5y ago
  [deleted]

Wistar 5y ago

I don't think that is true except, perhaps in the case of much older vehicles—particularly carbureted, rather than injected—vehicles. Most of the advice I have read in, say, the last 20 years for gasoline-powered vehicles, is to allow no more than about 30 seconds to a minute of standing warm up before gently driving off. The engine will be fully lubricated within 10-15 seconds and ready to go.

ashwagary 5y ago
>allow no more than about 30 seconds to a minute of standing This heavily depends on the temp range you are discussing. Lubrication is the least of your worries at certain temperatures. The engine block and pistons being too cold cause problematic expansion and contraction which can lead to block cracks or permanent engine knock issues from what I've seen. This will eventually lead to needing an engine replacement.
- londons_explore 5y ago
  But if driven hard while cold, it will warm up faster, reducing the damage that can be done. It's a trade-off, and nobody seems to have done the science properly - it's just mechanics and engineers guessing which effect is worse.
  - ashwagary 5y ago
    >But if driven hard while cold, it will warm up faster, reducing the damage that can be done. Is this sarcasm? I can't tell because it is literally the opposite of the truth.
ehnto 5y ago
You can actually hear my '96 motor quiet down as the oil makes it's way through the head. Takes about 15 seconds. I wait for the engine coolant temp to reach 75c before I give it a good wick. It fluctuates between 75c and 85c under good load. Interesting to me, is that when idling down a hill it does not drop, but if left in gear going down a hill it does drop in temp. It can actually get itself below operating temperature in gear going down a hill. I presume because the heat being pulled out via pumping air through the combustion chamber is greater than the thermostat would allow to be pulled out via the radiator.

dalkvist 5y ago

Witch is why you have an electric engine heater in cold(er) places, no need to idle :shrug: