Well, my engine is spec'd for 5w20... but with my newest intake addition, I figured a thicker oil may benefit (in case of poorer filtration). I'm pretty much a n00b when it comes to this type of stuff, so any input you have would be appreciated. My driving style consists 70% highway, 30% city. I do have a lot of mountainous back roads that I enjoy driving on as well. I'm not anti 5w20 by any means... I'm just thinking that the thicker oil may benefit my driving style & modifications. You tell me.