I own 4 cars, a 1994 Toyota 4x4 pickup, a 1996 Toyota Avalon, a 1999 and a 2000 Honda Accord. They all call for 5W30 oil on the oil caps and the manuals except the 94 pickup which requires 10W30 in the summer and 5W30 in the winter. I have been using 5W30 all these year on them and now I would...