Hey guys, So I've had the truck for about 2.5 months and I wanna do and O&F on her, but what do I use? Synth or regular? What weight? How much? 5 quarts? ...guess I'm really asking what does the factory say this thing should live on. Dean P.S. She's gettin' real close to 150k, but purrs like a kitten. Looks and drives like new. No leaks.