I first of all want to say that as a former resident in Oman and having made about 10 visits to the country since we left we have never experienced anything like this before. However, we would like to share this event so that others can beware.
On our recent holiday in Oman, March 2013, we drove into a petrol station in Sidab to fill up our car. One attendant was filling up a 4WD, the other one was doing nothing. This one waved to us to go to the man at the 4WD which we did. He filled our car up and when my husband went to pay him he was surprised to see that we were being charged for 45 litres of petrol. The car tank was almost half full and we were sure that this was more than it was possible to put in. We always keep a daily record of our distances and amounts paid so we had a good idea of how much it should have been. The attendants' command of English was not sufficient for us to argue our case but we made it clear that we believed this was not the correct amount, however we had no choice but to pay up. We realised after what had happened. The guy had not returned the pipe into the pump and so it had just continued on after the previous customer, meaning that we were being charged again for his petrol as well as our own - so a little profit on the side for the attendants. We did complain to the oil company but disappointingly did not receive any response from them. Commercial vehicles, including car hire, have different number plates from privately owned vehicles so it is obvious as you approach that you are in a hired car and probably a tourist. From the way these guys operated I do not believe this was the first time they had done it, but I stress we have never before experienced any deceit at a petrol pump, and indeed the men are usually extremely helpful and honest. An unfortunate experience leaving a nasty feeling.