A big rig has overturned on northbound Interstate Five south of Lakehead. A UPS truck with a full load of packages weighing about 75,000 pounds tipped over just after 2 O’clock Friday afternoon and it’s blocking the right lane of the freeway near the Gilman Road offramp. A lot of oil has spilled on the roadway and a Cal-Trans crew has been trying to contain it. Some traffic delays can be expected as a tow truck crew tries to upright the tractor-trailer and move it out of the traffic lanes.