Hi, I was given a 1999 Toyota Camry V6 from my father. I changed the oil myself, but the oil was very slow flowing and sludgy when draining. I have read that this vehicle is prone to sludge. I don't want to use any chemical cleaners on it. I was hoping to let a synthetic motor oil clean it. I had read about Penzoil Platinum Ultra, but that claim they make on cleanliness is very deceiving. They only focus on Piston cleanliness, which is only affected by the small amounts of oil that every engine burns when tiny amounts of oil flow past the pistons into the cylinders, and the smoke from that burned oil is a little cleaner when Penzoil Ultra burns. But that says nothing at all to what we really want a detergent oil to be: To clean out a sludge engine. So I had seen this link on Mobil 1's website: http://www.mobiloil.com/USA-English/MotorOil/Synthetics/Mobil_1_Sludge_Protection.aspx Mobil claims that in one 4,000 mile oil change with Mobil 1, that it can completely clean out a sludged engine. Could Mobil 1's claim be correct? Are there other oils that clean better than Mobil 1? I would prefer not to use any chemical cleaners, as they can dry out seals, and cause other issues. Thank you in advance for your advice.