engines
There are many internal combustion engines powered by gasoline, diesel, propane, or natural gas; hybrid vehicles, plug-in hybrids, hydrogen-powered fuel cell vehicles, and all-electric vehicles. Fuel-powered vehicles have an advantage due to their limited range and high battery costs. Some options require a network of refueling or charging stations.
An external sign of wear on the valve stem seals is the short-term appearance of blue smoke from the exhaust pipe after starting the engine and when braking the engine after a long drive under load