Motorists who ordered unleaded petrol at an Engen garage in Mamelodi West at the weekend had their fuel tanks filled with water.
Internal combustion engines won't run on water and the trouble started when they drove off.
Some were lucky to spot the problem immediately, but others came to an expensive stop a distance away from the station.
The first irate motorists approached the staff, but were given a tough time by perplexed attendants. But as the number of complaints grew the attendants drew samples from the unleaded fuel tank.
It was the colour of "litchi fruit juice", said one driver.
"We were told to wait for Engen Petroleum officials to arrive. Something told me that they might not come since it is a weekend," said an owner of a 3-Series BMW.
"I demanded a refund but I ended up spending more money to have the liquid flushed out. I also had to replace the petrol filter but my car will still not start."
Other stranded victims carried water-logged fuel filters back to the garage from stalled cars scattered throughout the township.
Angry motorists said the flustered manager protested that the "fuel" had been delivered at 2am on Saturday.
The manager refused to talk to Sowetan, but workers confirmed the problem.
Engen Petroleum also failed to respond to attempts to get comment.