3 ms·

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

by 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.
- bagels 5y ago
  Two factors, deceleration fuel cutoff in gear not producing combustion heat, and water pump spinning faster.
  - ehnto 5y ago
    I would have thought the thermostat would account for faster water flow, at least stopping the temperature drop at operating temp. But as another user pointed it, it could be a bad thermostat also.
- throwawaylinux 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. Pretty typical of engines of that vintage with hydraulic lifters. > 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. I didn't think that would significant but I could be wrong. Is it a diesel or gasoline engine? My guess would be the thermostat is leaking or wrong temperature.
WalterBright 5y ago
That's why when I get in the car I start the engine first, then fiddle about with the seatbelt, parking brake, getting settled, check the mirrors, etc. By the time I finish all that the car is ready to ease into gear.
- Wistar 5y ago
  Yep, that's my routine as well.

by Wistar 5y ago

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.

bagels 5y ago
Two factors, deceleration fuel cutoff in gear not producing combustion heat, and water pump spinning faster.
- ehnto 5y ago
  I would have thought the thermostat would account for faster water flow, at least stopping the temperature drop at operating temp. But as another user pointed it, it could be a bad thermostat also.
throwawaylinux 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. Pretty typical of engines of that vintage with hydraulic lifters. > 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. I didn't think that would significant but I could be wrong. Is it a diesel or gasoline engine? My guess would be the thermostat is leaking or wrong temperature.

WalterBright 5y ago

That's why when I get in the car I start the engine first, then fiddle about with the seatbelt, parking brake, getting settled, check the mirrors, etc. By the time I finish all that the car is ready to ease into gear.

Wistar 5y ago
Yep, that's my routine as well.