well i can share some about diesel engine starting
ppl used to give heaters before starting due to their engine health
Heaters should be engaged before starting after a long rest of engine like more
than 5 - 6 hours coz engine is cool and after that there is no need to give heaters
before starting but this is good when u got and old model diesel engine but in good health
as in todays era we have got new technology engine which do need heaters because an automatic
heater is installed in the in-let of air as we switch on it gets heated instantly and there is no need
to wait for heaters or light to be switched of
well using heater frequently decreases the life of battery and heater both but helps to get
the engine started quickly