The more I read the more it seems that Mobil 1 is a very thin oil, almost to thin. I would like to keep using it as it seems to be a "top of the line oil" and very easy to buy anywhere but would like it to be a little thicker. Right now I'm using Mobil 1 5w30 in both my Camaro ls1 and Chevy 5.3 vortec. I here some folks add 1 or 2 qts of 15w50 to 4 qts of 5w or 10w30 to thicken it up. So what weight does this make the oil now? Also does the 2 different weight oils seperate at all when in use or after the engine is off for a while or do they compleetly blend together permenitly? One more thing, would my engine be better protected by mixing Mobil 1 15w50 and the 5w30 vs. just straight 5w30 or 10w30 or would it not make much of a differance as far as protection goes and covering up knock and noise which I'm not sure if my engines are doing? Thanks again!