It's believed the oil ended up coating dozens of ducks that had to be rescued by wildlife volunteers.
Police say the transport rolled over Monday evening when the driver failed to properly get around a curve on a ramp at Highway 401 and Highway 427.
Three electrical transformers on the truck contained approximately 2,878 litres of oil each.
Police say at least two transformers spilled the oil onto the roadway and surrounding area.
Barry Kirkham, 54, from Sherwood Park, Alta., sustained minor injuries and was taken to hospital for assessment.
Workers with the Toronto Wildlife Centre rescued dozens of oil-covered ducks and set up two bathing stations to remove the oil.
Once the birds have been cleaned and deemed healthy, they'll be released back into the wild.
Also on HuffPost