Turn 1.  Sep/Oct 1939.  End of Turn.  Use Oil, CW.
 
 In order not to cut into their production the CW had to take care in which oil they used.  This is even more subtle that it seems as explained as follows.  The CW didn't want to use any oil currently saved in England, which is needed for production because of the disruption of convoy routes through the Med.  To not use the saved oil point required the CW to use two oil points "defaulted" for production to Glasgow and Birmingham.  On the surface that's ok because once they use these two oil points the convoys used to ship them from Canada to England are freed up and then could be used to ship two oil points from Venezuela "defaulted" for save in Canada.  However, since the oil points from Venezuela are "traded" resources this substitution (or change in production) 
MUST be done 
PRIOR to the final production phase, at which time no changes can be made to traded resources.  The subtle part is that changes to traded resources can still be made 
AFTER preliminary production during phases like use oil or even army/crops breakdown as long as one remembers to bring up the production form during one of those phases for the country in question.  For example, if one waited to the army/corps breakdown phase to change production but the country in question didn't have any units to breakdown then one has waited too long to make the changes.  It's best to do it during the use oil phase, which every country has, if one can remember.
 
 
