I'm new here and only have posted a few times but have a ton of question. Some that are going to be stupid for you guys but there is only one way to find the answer, ask. 1- I just bought a new toyota tundra with the 4.7l and will be towing a 3000# camper some this summer.I'am going to do my first oil change soon (at 2000) and thinking about running the mobil-1 5w40 truck/suv because everyone seens to think this oil is GREAT. Would running this oil hurt anything? The manual says 5w30 "or if that is not available" to run 10w30. 2- Now that gas is almost $2.00 a gallon how much differance in gas millage do you think there would be between 5w30 and the 5w40? 3-Or should I just stick with my first plan, mobil 5w30 and be done with it? I told you I had some stupid question!! Thanks for your time !!!