The service station will swipe your AA card 2x. They swipe once and you pay. Then they swipe the 2nd time and you pay the 2nd time. You might want to tell him/her to pay 2x separately and accumulate each. Saves you do a $40 run inside and pay, run out again and do $40 again and pay again.

Yes you accumulate it every single time until the end of the 2nd month when you redemn it at one go.

8c - before
8c - before
8c - before
8c - before
Let's say now you want to use it up. That is a total of 32c in the past. But today there is a 10c discount. You therefore get 42c in total.

FWIW. We don't use the car often, going to the CBD easier and cheaper to bus. When you do a full tank redemn. It takes us just over 1 month to use it up. So eg -

End of September we did a full tank.
That last to the first week of October.
October we do a $40 and we accumulate this.
The next 2nd month is November. So we use (redemn) all the points by the end of November. So you don't have to do it every 2 months. You can do it from the first time you accumulate - by the end of the next month your points expire.

But hey - waiting for specials is always good but there are times when you just fuelled up and the promotion happens - so you miss out. But hey that's life. But yeah with the standard 4c off, you can accumulate that up and use it up in one go... What we do is put just $40 in with normal price so when a special comes out we have half a tank empty for that. If our tank is pretty low and there is a promotion we may do 2x $40.