Hopefully I didn't screw up. I bought oil for my first oil change at Wal-Mart. I didn't check the API certification. After the oil change, I checked my owner's manual. The numbers aren't compatible. Did I screw up? What I bought was API certified at CG-4. The manual requires CG-4/SH. THe manual says "Do not use oil labeled with only one of the following category designations; SG, SH, CE, CF-4, or CG-4, as they could cause engine damage."
I don't know what all this means. The "only one" part of the quote confuses me. The oil I used was Castrol Tection 15W-40 Diesel engine oil with a Motorcraft filter. The oil has several API designations, including CG-4. Do I need to get this stuff out of my engine? I have run about 150 miles since the change before I read the manual.