--- a/src/company_cmd.cpp
+++ b/src/company_cmd.cpp
@@ -1170,3 +1170,21 @@
 
 	return CommandCost();
 }
+
+/**
+ * Get the service interval for the given company and vehicle type.
+ * @param c The company, or NULL for client-default settings.
+ * @param type The vehicle type to get the interval for.
+ * @return The service interval.
+ */
+int CompanyServiceInterval(const Company *c, VehicleType type)
+{
+	const VehicleDefaultSettings *vds = (c == NULL) ? &_settings_client.company.vehicle : &c->settings.vehicle;
+	switch (type) {
+		default: NOT_REACHED();
+		case VEH_TRAIN:    return vds->servint_trains;
+		case VEH_ROAD:     return vds->servint_roadveh;
+		case VEH_AIRCRAFT: return vds->servint_aircraft;
+		case VEH_SHIP:     return vds->servint_ships;
+	}
+}

--- a/src/order_cmd.cpp
+++ b/src/order_cmd.cpp
@@ -1819,9 +1819,9 @@
  * @param company_id the owner of the vehicle
  * @return Clamped service interval
  */
-uint16 GetServiceIntervalClamped(uint interval, CompanyID company_id)
+uint16 GetServiceIntervalClamped(uint interval, bool ispercent)
 {
-	return (Company::Get(company_id)->settings.vehicle.servint_ispercent) ? Clamp(interval, MIN_SERVINT_PERCENT, MAX_SERVINT_PERCENT) : Clamp(interval, MIN_SERVINT_DAYS, MAX_SERVINT_DAYS);
+	return ispercent ? Clamp(interval, MIN_SERVINT_PERCENT, MAX_SERVINT_PERCENT) : Clamp(interval, MIN_SERVINT_DAYS, MAX_SERVINT_DAYS);
 }
 
 /**

--- a/src/order_func.h
+++ b/src/order_func.h
@@ -33,6 +33,6 @@
 #define MIN_SERVINT_DAYS    30
 #define MAX_SERVINT_DAYS   800
 
-uint16 GetServiceIntervalClamped(uint interval, CompanyID company_id);
+uint16 GetServiceIntervalClamped(uint interval, bool ispercent);
 
 #endif /* ORDER_FUNC_H */

--- a/src/saveload/vehicle_sl.cpp
+++ b/src/saveload/vehicle_sl.cpp
@@ -17,6 +17,8 @@
 #include "../aircraft.h"
 #include "../station_base.h"
 #include "../effectvehicle_base.h"
+#include "../company_base.h"
+#include "../company_func.h"
 
 #include "saveload.h"
 
@@ -349,6 +351,19 @@
 				v->cargo_age_counter = _age_cargo_skip_counter;
 			}
 		}
+
+		if (IsSavegameVersionBefore(180)) {
+			/* Set service interval flags */
+			FOR_ALL_VEHICLES(v) {
+				if (!v->IsPrimaryVehicle()) continue;
+
+				const Company *c = Company::Get(v->owner);
+				int interval = CompanyServiceInterval(c, v->type);
+
+				v->SetServiceIntervalIsCustom(v->GetServiceInterval() != interval);
+				v->SetServiceIntervalIsPercent(c->settings.vehicle.servint_ispercent);
+			}
+		}
 	}
 
 	CheckValidVehicles();

--- a/src/vehicle.cpp
+++ b/src/vehicle.cpp
@@ -111,7 +111,7 @@
 
 	/* Are we ready for the next service cycle? */
 	const Company *c = Company::Get(this->owner);
-	if (c->settings.vehicle.servint_ispercent ?
+	if (this->ServiceIntervalIsPercent() ?
 			(this->reliability >= this->GetEngine()->reliability * (100 - this->GetServiceInterval()) / 100) :
 			(this->date_of_last_service + this->GetServiceInterval() >= _date)) {
 		return false;

--- a/src/vehicle_base.h
+++ b/src/vehicle_base.h
@@ -648,6 +648,14 @@
 	inline uint16 GetServiceInterval() const { return GB(this->service_interval, 0, 16); }
 	inline void SetServiceInterval(uint16 interval) { SB(this->service_interval, 0, 16, interval); }
 
+	inline bool ServiceIntervalIsCustom() const { return HasBit(this->service_interval, 31); }
+
+	inline bool ServiceIntervalIsPercent() const { return HasBit(this->service_interval, 30); }
+
+	inline void SetServiceIntervalIsCustom(bool on) { SB(this->service_interval, 31, 1, on); }
+
+	inline void SetServiceIntervalIsPercent(bool on) { SB(this->service_interval, 30, 1, on); }
+
 private:
 	/**
 	 * Advance cur_real_order_index to the next real order.

--- a/src/vehicle_cmd.cpp
+++ b/src/vehicle_cmd.cpp
@@ -30,6 +30,7 @@
 #include "order_backup.h"
 #include "ship.h"
 #include "newgrf.h"
+#include "company_base.h"
 
 #include "table/strings.h"
 
@@ -1030,7 +1031,10 @@
  * @param tile unused
  * @param flags type of operation
  * @param p1 vehicle ID that is being service-interval-changed
- * @param p2 new service interval
+ * @param p2 bitmask
+ * - p2 = (bit  0-15) - new service interval
+ * - p2 = (bit 16)    - service interval is custom flag
+ * - p2 = (bit 17)    - service interval is percentage flag
  * @param text unused
  * @return the cost of this operation or an error
  */
@@ -1042,11 +1046,22 @@
 	CommandCost ret = CheckOwnership(v->owner);
 	if (ret.Failed()) return ret;
 
-	uint16 serv_int = GetServiceIntervalClamped(p2, v->owner); // Double check the service interval from the user-input
-	if (serv_int != p2) return CMD_ERROR;
+	const Company *company = Company::Get(v->owner);
+	bool iscustom  = HasBit(p2, 16);
+	bool ispercent = iscustom ? HasBit(p2, 17) : company->settings.vehicle.servint_ispercent;
+
+	uint16 serv_int;
+	if (iscustom) {
+		serv_int = GB(p2, 0, 16);
+		if (serv_int != GetServiceIntervalClamped(serv_int, ispercent)) return CMD_ERROR;
+	} else {
+		serv_int = CompanyServiceInterval(company, v->type);
+	}
 
 	if (flags & DC_EXEC) {
 		v->SetServiceInterval(serv_int);
+		v->SetServiceIntervalIsCustom(iscustom);
+		v->SetServiceIntervalIsPercent(ispercent);
 		SetWindowDirty(WC_VEHICLE_DETAILS, v->index);
 	}
 

--- a/src/vehicle_func.h
+++ b/src/vehicle_func.h
@@ -176,4 +176,6 @@
 
 void CheckCargoCapacity(Vehicle *v);
 
+int CompanyServiceInterval(const Company *c, VehicleType type);
+
 #endif /* VEHICLE_FUNC_H */

--- a/src/vehicle_gui.cpp
+++ b/src/vehicle_gui.cpp
@@ -1687,6 +1687,8 @@
 				SetDataTip(AWV_DECREASE, STR_VEHICLE_DETAILS_DECREASE_SERVICING_INTERVAL_TOOLTIP),
 		NWidget(WWT_PUSHARROWBTN, COLOUR_GREY, WID_VD_INCREASE_SERVICING_INTERVAL), SetFill(0, 1),
 				SetDataTip(AWV_INCREASE, STR_VEHICLE_DETAILS_INCREASE_SERVICING_INTERVAL_TOOLTIP),
+		NWidget(WWT_TEXTBTN, COLOUR_GREY, WID_VD_DEFAULT_SERVICING_INTERVAL), SetFill(0, 1),
+				SetDataTip(STR_BUTTON_DEFAULT, 0),
 		NWidget(WWT_PANEL, COLOUR_GREY, WID_VD_SERVICING_INTERVAL), SetFill(1, 1), SetResize(1, 0), EndContainer(),
 		NWidget(WWT_RESIZEBOX, COLOUR_GREY),
 	EndContainer(),
@@ -1711,6 +1713,8 @@
 				SetDataTip(AWV_DECREASE, STR_VEHICLE_DETAILS_DECREASE_SERVICING_INTERVAL_TOOLTIP),
 		NWidget(WWT_PUSHARROWBTN, COLOUR_GREY, WID_VD_INCREASE_SERVICING_INTERVAL), SetFill(0, 1),
 				SetDataTip(AWV_INCREASE, STR_VEHICLE_DETAILS_DECREASE_SERVICING_INTERVAL_TOOLTIP),
+		NWidget(WWT_TEXTBTN, COLOUR_GREY, WID_VD_DEFAULT_SERVICING_INTERVAL), SetFill(0, 1),
+				SetDataTip(STR_BUTTON_DEFAULT, 0),
 		NWidget(WWT_PANEL, COLOUR_GREY, WID_VD_SERVICING_INTERVAL), SetFill(1, 1), SetResize(1, 0), EndContainer(),
 	EndContainer(),
 	NWidget(NWID_HORIZONTAL),
@@ -1984,7 +1988,7 @@
 				SetDParam(0, v->GetServiceInterval());
 				SetDParam(1, v->date_of_last_service);
 				DrawString(r.left + WD_FRAMERECT_LEFT, r.right - WD_FRAMERECT_RIGHT, r.top + (r.bottom - r.top + 1 - FONT_HEIGHT_NORMAL) / 2,
-						Company::Get(v->owner)->settings.vehicle.servint_ispercent ? STR_VEHICLE_DETAILS_SERVICING_INTERVAL_PERCENT : STR_VEHICLE_DETAILS_SERVICING_INTERVAL_DAYS);
+						v->ServiceIntervalIsPercent() ? STR_VEHICLE_DETAILS_SERVICING_INTERVAL_PERCENT : STR_VEHICLE_DETAILS_SERVICING_INTERVAL_DAYS);
 				break;
 		}
 	}
@@ -2007,6 +2011,8 @@
 			WID_VD_DECREASE_SERVICING_INTERVAL,
 			WIDGET_LIST_END);
 
+		this->SetWidgetLoweredState(WID_VD_DEFAULT_SERVICING_INTERVAL, !v->ServiceIntervalIsCustom());
+
 		this->DrawWidgets();
 	}
 
@@ -2027,10 +2033,20 @@
 				const Vehicle *v = Vehicle::Get(this->window_number);
 
 				mod = (widget == WID_VD_DECREASE_SERVICING_INTERVAL) ? -mod : mod;
-				mod = GetServiceIntervalClamped(mod + v->GetServiceInterval(), v->owner);
+				mod = GetServiceIntervalClamped(mod + v->GetServiceInterval(), v->ServiceIntervalIsPercent());
 				if (mod == v->GetServiceInterval()) return;
 
-				DoCommandP(v->tile, v->index, mod, CMD_CHANGE_SERVICE_INT | CMD_MSG(STR_ERROR_CAN_T_CHANGE_SERVICING));
+				DoCommandP(v->tile, v->index, mod | (1 << 16) | (v->ServiceIntervalIsPercent() << 17), CMD_CHANGE_SERVICE_INT | CMD_MSG(STR_ERROR_CAN_T_CHANGE_SERVICING));
+				break;
+			}
+
+			case WID_VD_DEFAULT_SERVICING_INTERVAL: {
+				const Vehicle *v = Vehicle::Get(this->window_number);
+				if (_ctrl_pressed) {
+					DoCommandP(v->tile, v->index, v->service_interval | (1 << 16) | (!v->ServiceIntervalIsPercent() << 17), CMD_CHANGE_SERVICE_INT | CMD_MSG(STR_ERROR_CAN_T_CHANGE_SERVICING));
+				} else {
+					DoCommandP(v->tile, v->index, v->service_interval | (!v->ServiceIntervalIsCustom() << 16) | (v->ServiceIntervalIsPercent() << 17), CMD_CHANGE_SERVICE_INT | CMD_MSG(STR_ERROR_CAN_T_CHANGE_SERVICING));
+				}
 				break;
 			}
 

--- a/src/widgets/vehicle_widget.h
+++ b/src/widgets/vehicle_widget.h
@@ -49,6 +49,7 @@
 	WID_VD_TOP_DETAILS,                 ///< Panel with generic details.
 	WID_VD_INCREASE_SERVICING_INTERVAL, ///< Increase the servicing interval.
 	WID_VD_DECREASE_SERVICING_INTERVAL, ///< Decrease the servicing interval.
+	WID_VD_DEFAULT_SERVICING_INTERVAL,  ///< Toggle default servicing interval.
 	WID_VD_SERVICING_INTERVAL,          ///< Information about the servicing interval.
 	WID_VD_MIDDLE_DETAILS,              ///< Details for non-trains.
 	WID_VD_MATRIX,                      ///< List of details for trains.