Why YSK: People seem to, on average, think that a car takes a lot of fuel to start up. In reality, it takes on the order of a few millilitres of fuel to start an engine. That means if your car isn’t equipped with an automatic start/stop system to stop your engine instead of idling, it saves fuel to turn off your engine and start it back up when you need it.
Caveat: air conditioning and radio might not work with the engine turned off.
Scenarios where this might be useful include waiting for trains to pass at rail crossings, waiting for food at drive-throughs, dropping off or picking people up on the side of the road when they need to load stuff, etc. May not be a good idea to use this while waiting at a red light because starting the engine does take time which would annoy drivers behind you when the light turns green.
Some cars are equipped with systems that will automatically stop the engine when you are idling for a while (e.g. waiting for a red light). If yours is, then manually turning off your engine will probably result in reduced fuel savings compared to just relying on the car to do it for you.
That’s not true, cold starts cause wear not warm starts.
At most it’s starter motor and battery wear, start stop cars have agm batteries for that reason.
Cold starts cause more wear than warm starts, but a warm start still causes a lot of wear because the engine doesn’t have oil pressure when it’s off, so it doesn’t have good lubrication until it turned over a few times.
Besides that, my car and many others will happily stop the engine on their own even before reaching operating temperature. At least I can turn it off with a single button instead of going through a menu on a touch screen.
Hmm while its true it wont have oil pressure, for the short time its stopped there would still be oil on the bigend bearing to crankshaft interface and on the cylinder walls, and oil pressure will be restored quickly before going above idle as the oil pump is primed.
And a heavier duty starter that is specifically made to be used often.
What about the fact that the oil drains to the pan in those few seconds that the engine is stopped?
This is my real concern. Sure you can upgrade starter motors and batteries to handle the extra cycles, but you can’t do anything about increased scoring and wear on cylinders in the milliseconds before the fluids start to circulate again.
Some start stop engines have auxiliary oil pumps. I don’t know much about them besides random research I have done in the past out of curiosity.
Napa also claims some vehicles have auxiliary water and transmission pumps as well.