Engine overheating

Very slim. Coolant sealants in a bottle do more harm than good under most cases.

Four cylinder front wheel drive automatic 78,000 miles.

My radiator fan works fine sometimes. When I go on long trips my engine overheats and I notice the fan is not on while the car is running. But sometimes the fan kicks in. what can be the problem?

May be a sticking relay. it is the cheapest and easiest fix. your cooling fan relay is located in the under hood fuse/relay block.