A harvesting header includes a header frame, rotary cutters carried by the header frame, a gearbox containing at least one gear coupled to each rotary cutter, and an electronic sensor to indicate an amount of oil in the gearbox. Each rotary cutter has a rotating disc with at least one blade for cutting crops. An agricultural vehicle includes a vehicle frame, at least one attached to the vehicle frame, and a harvesting header coupled to the vehicle frame by a plurality of hydraulic cylinders. A method of operating an agricultural vehicle includes adjusting at least one hydraulic cylinder to move a header frame to a known orientation, sensing a position of an oil surface in a gearbox, and determining or indicating an amount of oil in the gearbox based at least in part on the position of the oil surface.

A method for evaluating the lubrication of friction components of an apparatus which can be lubricated by means of a lubricant circuit. A lubricant pump of the lubricant circuit is drivable by a drive engine. A pressure ascertainment unit continuously ascertains the lubricant pressure at at least one defined region of the lubricant circuit during an engine start procedure. A travel ascertainment unit is provided, by means of which at multiple pressure points in time, at each of which the lubricant pressure ascertained exceeds a defined pressure limiting value (p.sub.1, p.sub.2, p.sub.3), the relative travel between the friction components since the beginning of the engine start procedure is ascertained or estimated, and an analysis unit, by means of which an evaluation value, is ascertained from the total of the relative travel values (.sub.1, .sub.2, .sub.3) ascertained at the pressure points in time.

A method for evaluating the lubrication of friction components of an apparatus which can be lubricated by means of a lubricant circuit. A lubricant pump of the lubricant circuit is drivable by a drive engine. A pressure ascertainment unit continuously ascertains the lubricant pressure at at least one defined region of the lubricant circuit during an engine start procedure. A travel ascertainment unit is provided, by means of which at multiple pressure points in time, at each of which the lubricant pressure ascertained exceeds a defined pressure limiting value (p.sub.1, p.sub.2, p.sub.3), the relative travel between the friction components since the beginning of the engine start procedure is ascertained or estimated, and an analysis unit, by means of which an evaluation value, is ascertained from the total of the relative travel values (.sub.1, .sub.2, .sub.3) ascertained at the pressure points in time.