mobil 1 5w30 and even dino 10w30...i know what the recommendation chart says for conventional oils and my engine. oil change pattern went something like this......m1-10-30 (6k), walmart bulk supertech 10w30-4k, maxlife conve. 10w30-4.5k (lots of low stress highway), mobil 1 5w30 6.7k, maxlife conv. 10w40---within 200 miles.....the maxlife 10w30 rates moderately high on kinematic viscosity, as opposed to the m1 w30s, which are almost in 20 weight territory....anyone care to venture a guess as to why all of the following oils except the w40 made NO difference in valve sounds? i want to try some of the german castrol ow30 the oil nerds like to ejaculate about at the next oil change as the k-viscosity is around 12.2....quite near to being in the 40 weight category, but if the mobil 1 w40 can quiet more.....i'll get some of that.