1996 sierra 2500 heats up going up hills but not on level or down gerades
no oil in engine or water in radiator will cause engine to seriously o/heat! and eventually seize! major engine damage!!
The engine would heat up quicker without the heater on but ever so slightly, so it probably doesn't matter.
Just for show, and to build up speed and engine heat.
Tires can heat up by around 50-100 degrees Fahrenheit when driving due to friction with the road surface.
If by this you mean only "hot heat" when drive at highway speeds likely thermostat bad and/or almost stuck and takes long time warm up from high engine RPM during highway driving.
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No engine likes being pushed too hard. The biggest problem most have is that people do not let the engine warm up first before driving this means letting the car idle for at least 5 minutes before driving anywhere. So in answering your question an engine will perform in both circumstances as long as you keep it regularly seviced and warm it up first before driving and you will have many more trips to go.
Auto experts today say that you should warm up the car no more than 30 seconds before you start driving in winter. "The engine will warm up faster being driven," the EPA and DOE explain.
It is not wise to drive with a blown head gasket. If you continue driving with a blown gasket, eventually your car will over heat and the engine will seize up. This can cause accidents if it occurs while driving.
Needs a new thermostat
Heat is built up while driving and that will increase pressure in the tires.
You don't HAVE to heat up the car before changing the oil. The only reason for doing this is that it "thins" out the oil and it will drain faster. If you aren't in a hurry, don't worry about it and just give it a little more time.