Same thing happened to me last Friday,July 28 back side of San Jose Airport road,looked like a truck or bus lost it's fuel,talk about sliding when making a left hand turn from Central Expressway to get the Hwy 101 ramp. Ride safe,you should have called the CHP and tell them the location of the oil spill,this way your message will be recorded and if there were a accident involving a motorcycle at the same spot it would be on record.