Index: src/engine.cpp
===================================================================
--- src/engine.cpp	(revision 14659)
+++ src/engine.cpp	(working copy)
@@ -72,6 +72,8 @@
 	if (base >= _engine_counts[type]) {
 		/* Mark engine as valid anyway */
 		this->info.climates = 0x80;
+		/* Set model life to maximum to make wagons available */
+		this->info.base_life = 0xFF;
 		return;
 	}
 
@@ -86,6 +88,10 @@
 			this->u.rail = _orig_rail_vehicle_info[base];
 			this->image_index = this->u.rail.image_index;
 			this->info.string_id = STR_8000_KIRBY_PAUL_TANK_STEAM + base;
+
+			/* Set the default model life of wagons to the maximum (usually infinite) */
+			if (this->type == VEH_TRAIN && this->u.rail.railveh_type == RAILVEH_WAGON) this->info.base_life = 0xff;
+
 			break;
 
 		case VEH_ROAD:
@@ -264,11 +270,7 @@
 
 		e->reliability_spd_dec = ei->decay_speed << 2;
 
-		if (IsWagon(e->index)) {
-			e->age = 0xFFFF;
-		} else {
-			CalcEngineReliability(e);
-		}
+		CalcEngineReliability(e);
 
 		e->lifelength = ei->lifelength + _settings_game.vehicle.extend_vehicle_life;
 
@@ -451,7 +453,7 @@
 		Engine *e;
 		FOR_ALL_ENGINES(e) {
 			/* Age the vehicle */
-			if (e->flags & ENGINE_AVAILABLE && e->age != 0xFFFF) {
+			if (e->flags & ENGINE_AVAILABLE) {
 				e->age++;
 				CalcEngineReliability(e);
 			}