I am thinking about just using Mobil 1 10W-30 in my car. I have used it before and the car ran good with it. I am using the German Castrol right now but it is just too hard to locate-it is kind of silly going from one AutoZone Store to another trying to locate it. The Schaeffer's oil is good but you have to pay shipping costs. Right now Mobil 1 is $18.80 a five quart jug at Wal-Mart. I figure that Mobil 1 10W-30 should be okay for summer driving. I did not like the 5W-30 Mobil 1-it seemed to be too thin in my car. But that was an older formula of Mobil 1 anyway. Some people at this site say that Mobil 1 is too thin. But Schaeffer's #132 will thicken it up some, right? How much Schaeffer's #132 do you use per 4 quarts of oil? Are the wear figures low enough with Mobil 1 so maybe you don't even need Schaeffer's #132? And can you use Auto-RX in Mobil 1 with maybe some Schaeffer's #132 added as well? A maintenance dose of 3 oz. of Auto-RX. I was really impressed with Auto-RX. I live in Colorado where the temperatures vary a lot from one season to another. Right now we have been having 100 degree days most days for quite a while, with high temperatures of 109, 108, 106, etc. In the wintertime it can get pretty cold-I have personally seen temperatures of -28. Would Mobil 1 10W-30 be okay year-round, or maybe Mobil 1 5W-30 in the wintertime?