diff --git a/src/autoreplace_func.h b/src/autoreplace_func.h
--- a/src/autoreplace_func.h
+++ b/src/autoreplace_func.h
@@ -16,8 +16,8 @@
 #include "company_base.h"
 
 void RemoveAllEngineReplacement(EngineRenewList *erl);
-EngineID EngineReplacement(EngineRenewList erl, EngineID engine, GroupID group);
-CommandCost AddEngineReplacement(EngineRenewList *erl, EngineID old_engine, EngineID new_engine, GroupID group, DoCommandFlag flags);
+EngineID EngineReplacement(EngineRenewList erl, EngineID engine, GroupID group, bool *replace_when_old = NULL);
+CommandCost AddEngineReplacement(EngineRenewList *erl, EngineID old_engine, EngineID new_engine, GroupID group, bool replace_when_old, DoCommandFlag flags);
 CommandCost RemoveEngineReplacement(EngineRenewList *erl, EngineID engine, GroupID group, DoCommandFlag flags);
 
 /**
@@ -34,12 +34,13 @@ static inline void RemoveAllEngineReplac
  * @param c company.
  * @param engine Engine type.
  * @param group The group related to this replacement.
+ * @param[out] replace_when_old Set to true if the replacement should be done when old.
  * @return The engine type to replace with, or INVALID_ENGINE if no
  * replacement is in the list.
  */
-static inline EngineID EngineReplacementForCompany(const Company *c, EngineID engine, GroupID group)
+static inline EngineID EngineReplacementForCompany(const Company *c, EngineID engine, GroupID group, bool *replace_when_old = NULL)
 {
-	return EngineReplacement(c->engine_renew_list, engine, group);
+	return EngineReplacement(c->engine_renew_list, engine, group, replace_when_old);
 }
 
 /**
@@ -55,17 +56,32 @@ static inline bool EngineHasReplacementF
 }
 
 /**
+ * Check if a company has a replacement set up for the given engine when it gets old.
+ * @param c Company.
+ * @param engine Engine type to be replaced.
+ * @param group The group related to this replacement.
+ * @return True if a replacement when old was set up, false otherwise.
+ */
+static inline bool EngineHasReplacementWhenOldForCompany(const Company *c, EngineID engine, GroupID group)
+{
+	bool replace_when_old;
+	EngineReplacement(c->engine_renew_list, engine, group, &replace_when_old);
+	return replace_when_old;
+}
+
+/**
  * Add an engine replacement for the company.
  * @param c Company.
  * @param old_engine The original engine type.
  * @param new_engine The replacement engine type.
  * @param group The group related to this replacement.
+ * @param replace_when_old Replace when old or always?
  * @param flags The calling command flags.
  * @return 0 on success, CMD_ERROR on failure.
  */
-static inline CommandCost AddEngineReplacementForCompany(Company *c, EngineID old_engine, EngineID new_engine, GroupID group, DoCommandFlag flags)
+static inline CommandCost AddEngineReplacementForCompany(Company *c, EngineID old_engine, EngineID new_engine, GroupID group, bool replace_when_old, DoCommandFlag flags)
 {
-	return AddEngineReplacement(&c->engine_renew_list, old_engine, new_engine, group, flags);
+	return AddEngineReplacement(&c->engine_renew_list, old_engine, new_engine, group, replace_when_old, flags);
 }
 
 /**