An oil truck has spilt 1000 litres of animal fat in what has already been a horror day on Sydney roads.
The spill happened at Mullens Road in Rozelle around 4.30pm.
Nobody was injured but emergency crews are trying to clean it up as the evening traffic builds.
Earlier today, a man was trapped on the Eastern Distributor at Moore Park.
Paramedics worked to free the driver after the crash happened around 12.30pm on Thursday.
Southbound lanes were closed, creating more traffic chaos following a car flip that brought peak-hour traffic to a halt.
The Sydney Harbour tunnel has reopened after the car accident blocked all south-bound lanes, shortly after 7.30am.
The car flipped onto its roof about 200 metres from the mouth of the tunnel at its southern exit.
Traffic quickly banked up from Sydney's north, causing heavy delays and queues of up to ten kilometres.
The accident also affected public transport, with some bus routes experiencing one-hour delays.
The driver suffered a minor neck injury and was taken to St Vincent's Hospital.
It is understood the crash happened when the driver, who was not feeling well, attempted to merge into the tunnel's left-hand breakdown lane.
Police said he misjudged the end of the lane and hit a safety wall, flipping the car onto its roof.
A doctor stopped and helped the man, aged in his 50s, until emergency services arrived.
He was not seriously injured.
The tunnel was closed to motorists until just after 9am, while the wreckage was removed and oil on the road way cleaned up.
Some minor damage to the tunnel has also been repaired.
The NSW Ambulance said paramedics were called to at least 40 road incidents across the state by 1pm on Thursday.
It comes as NSW drivers are being urged to slow down, especially in the wet, stay awake and put phones away in an effort to avoid a repeat of last year's June holiday road toll.
Six people were killed on the state's roads during the 2013 Queen's birthday long weekend, up from two the previous year.
"Six people including a driver, a pedestrian, a cyclist and a rider - these were all people who were either mothers or fathers or sons or daughters, and they all lost their lives on our roads," NSW Police Deputy Commissioner Catherine Burn told reporters on Thursday.
Double-demerit points and extra police officers will be in place from midnight Thursday through to midnight Monday for Operation Stay Alert, which will target speeding, drink-driving, fatigue, seatbelt use and driver distraction.
Ms Burn said the state's road toll for 2014 already stands at 148, compared with 130 this time last year.
Police Minister Stuart Ayres said drivers needed to look out for one another.
"The key message to people is to slow down, to take consideration of the conditions, particularly on a day like today where we've seen the change in weather conditions has really changed the way people drive and people have not reacted well to that," he said.
"Take care of your family, take care of your friends and do not become a statistic."
The warning comes after a crash in the Sydney Harbour tunnel forced the city's centre into near-lockdown during the Thursday morning peak.
Mr Ayres said new roads were in the works to help "detangle" Sydney's traffic network but personal responsibility was key.
"We're investing billions and billions of dollars in new road infrastructure to make our city work more effectively but at the end of the day, when you're driving your own car, you've got to take responsibility for what you're doing," he said.