For the X/290 (and the later X/250 with DPF), there are two different Service Intervals used. (and displayable on the dash by toggling the service display)
The first, the general service interval, has settings accessed by the "Service" option in
MultiECUscan, and the "Next Service KM Reset" option should be used as and when a general service has been undertaken to reset the time/distance to the next service. This "Service" option in
MultiECUscan also allows adjustment of the general service
interval - (via "Service Interval") I understand this interval might be different in different markets (48,000km on mine).
The second service interval is that for oil service. It is in the "Engine" option in
MultiECUscan, under "Oil Change, Only for Versions with DPF" and should be reset (only) when an oil change is carried out. As oil change requirement is "condition based", depending on the way a vehicle is driven the requirement for an oil change may not coincide with the time/mileage for the general service. The engine ECU calculates usage patterns and decides when an oil change is required. Using the "Oil Change" option sets the calculation back to base, from which calculation restarts. Hence the necessity to use this option only at an actual oil change, with clean oil being the starting point. Unlike the general service option, there is no way of setting different parameters for the oil-change time/distance.