It literally means the oil that keeps the car's engine cool is running hotter than normal.
I means you are feeling hot as popping
If it is for the older air cooled engines, it means you are running hot and running hot means no oil.
15w means they are the viscosity (flow) when the oil is cold, the -30 and -40 is the viscosity of the oil when hot. Therefore the 15w-30 being the lower Viscosity means it will flow fast then the 15w-40 when the oil is hot.
That means the oil is 15 weight when cold and 40 weight when hot. The higher the number the thicker the oil.
If it runs to hot or very hot for a long time the engine head gasket will fail. You can check this by looking for excessive water or steam out of the exhaust or if there is antifreeze/water in your oil (checked by looking on the dipstick).
68 weight is the most common
check oil for water and radiator for oil, if engine oil has water miced with it ,the oil will be milky looking same does for radiator
Your oil is hot.
Deep frying means you submerge the food in hot oil. Most restaurant have friers that have baskets for the food and then you lower the basket into the oil. At home you need a pot deep enough to submerge the food in the hot oil without it boiling over.
That means that you need to change the oil filter. Or, it could mean that the combustion of the oil is out of tune, and you need to have a qualified oil burner technician look at it.
at what temperature does motorcycle oil suppose to get hot
Typically this means the oil level is low. Often can come on on steep inclines as the oil runs away from the sensor.