Hello, I'm new to this forum. I have a 2012 GMC Sierra with 150,000 miles. The 5.3 litre engine has had the oil changed every time the oil life has hit 30% , around 5 to 6 thousand miles. The oil pressure dropped and I replaced the oil pressure sending unit (opsu) and the problem was fixed for about a month. The old screen filter under the opsu was dirty but not severely clogged. After about a month the oil pressure dropped to 20 lbs and the check engine light came back on. I am considering pulling the opsu back out , @ operating temperature, and squirting brake cleaner or something down the oil passage followed by 2 hot oil changes. My question is , 1: is this a good idea?, 2: where does that oil passage directly lead to?