Ok, here goes! I just put Delvac 1 in my truck, it has 9k on the engine, how long should I wait to do a UOA? Whats the fundmental difference between a 0W30 and a 5W40 that would raise the oil pressure by 5psi at operting temp? Finally, seeing that my engine is still breaking in, can I leave the oil in for an extended time-or should I change it regularly? Ive searched this site quite a bit and have absorbed a lot of info, and actually understand about 1/3 of it! So your help is greatly appreciated!