Well i have been using some of that maxlife syn i bought at an el cheapo price a few months ago. I have noticed that on the first start of the day that i get a noticeable valve tick or a possible light engine knock. HMMMM. Im using an origional DANA WIX filter for the first time also. The vehicle is a 91 GMC PU 1500 4.3 engine 105,000 miles. I have had this vehicle for over 10 years and i know its quirks. I have also noticed that the oil pressure ,with a warm engine, at idle is much lower, say 18-20 psi versus 25-30 psi, than usual but it runs fine and is not starving for oil. At at speed of say 70 mph i have noticed that the oil pressure is at 32 psi versus 37-39 with other oil/filter combos. Like i said no problems but i wonder if this syn is actually a sin for my engine or could it be the filter? I have used penz, qs, castrol, st oil and dreaded fram, st, purolator and penske oil filters in the past with no problems. When i hit 5k on this oil im gonna put in some Free after rebate qs sl 10/30 and a st filter and see what happens. In case i forgot to say this oil is 5/30 maxlife syn and a wix filter, both of which im using for the first time in this engine.