Gobs of a gooey, sticky, oily tarlike substance caked on several hundred vehicles Tuesday night traveling the Pennsylvania Turnpike over a nearly 40-mile stretch that included a portion of southern Butler County.

“We’ve gotten hundreds of calls,” state police Cpl. Eric R. Sebastian said this morning while manning phone lines at the Gibsonia barracks.

The source of the gunky mess was a tanker truck hauling driveway sealant, according to Turnpike Commission spokesman Bill Capone.

It appeared a valve broke or malfunctioned on the tanker about 8 p.m. as it hit the turnpike at the New Castle exit, Capone said.

Unaware of the trouble, the driver of the truck from MTS Transport in Stevensville, Md., continued eastbound to the Oakmont service plaza.

Some drivers unlucky to be behind the truck had trouble keeping their vehicles from sliding off the highway. Even worse, their tires, wheel wells and undercarriages were covered in goop.

Several vehicles were so coated that they couldn’t move, police said.

So many vehicles were affected that the Pennsylvania Turnpike Commission set up a toll-free telephone number, 1-800-331-3414, to help the victims.

Traffic by rush hour this morning was moving normally, according to turnpike officials.