I have a question that I know you guys can help me with. I realized when I did my oil change recently at the dealer that they put in 10W-30 oil instead of the 5W-30 Synthetic-Blend they put in other times. I'm a little upset about the switch, they should have told me. My question is that on the next oil change, I do them every 5,000 miles, if I ask them to use the 5w-30 Synthetic-Blend will this affect anything in the engine that ran with 10W-30? I have 40,000 on my truck.