I use 5W30 for my 2007 Toyota Tacoma, which has about 120K mi. Someone told me that I should put 10W30 because the vehicle is "not very new". Is that a good approach? I've never had problems with 5W30.
Bottom line is, if your vehicle is running good with 5w30, why would you want to change it? If it's the weight which is specified for it to run/behave properly, this is what you should be using. Engines are made with certain clearances to utilize certain oils. When you start messing with this, you are introducing a possible problem for your engine. Besides, your friend doesn't understand oil too well. 5w-30 and 10w-30 are both 30 weight oil. When they are warm, they will both flow the same. The difference is their cold viscosity rating. It would especially not do your engine any good to put the thicker winter weight oil into the vehicle (assuming you are gaining on winter where you are at). The thicker oil when cold will not flow as well as the 5w-30, which means your engine will remain oil starved longer at start up, causing it to achieve more wear. Not good all the way around.