Sears Club is devaluing their program as of 1/Feb. To account for the devaluation, they will be adjusting point balances to match the old redemption value. So, for example, 5K points previously got you a $100 GC, so they will adjust a 5K balance to 10K, which is the new redemption value for a $100 GC. See http://searscard.sears.ca/2Xpoints.

They have not made any announcements about changes to the PetroPoints <-> Sears Club exchange rate, so this deal is based on the assumption that this doesn't change.

If that's true, then:

40K PP -> 2K Sears -> adjust 3K Sears -> 60K PP
100K PP -> 5K Sears -> adjusted 10K Sears -> 200K PP (double)
240K PP -> 12K Sears -> adjusted 36K Sears -> 720K PP (triple)

Remember that 200K PP = 20K CX and 720K PP = 72K CX.