I changed oil today on my truck because I needed a sample for blackstone to double check for glycol they found in my last UOA. I was using 15w-40 LL pennzoil which showed quite more pressure when at operating temperature and at highway speed and at idle. Does less oil pressure mean less protecton on bearings and other critical parts or not? Forgive me if this is a dumb question but I have to know. I had some extra castrol 10w-30 around so I decided to use it. My wife said my oil shrine was starting to make a visual mess in the basement.