Just returned from a 7,114 mile cross country trip in our 95 Chevy Sportvan, running the same batch of QS Defy 10w30. Oil hit long pull 13,600 mountains, and also 4 hours of stop and go in both Los Angeles and Chicago. Oil isn't overly dark, and I will be sending it in just for reference. It also sealed up a leaky Rear main along the way!
Now for my observation. After about 3-3500 miles, the engine would drain back oil pressure after each shut off. As most engines have a slight knock after a fresh oil change for first start, this was doing it after every restart. Oil pressure when running however was about 45psi, and never fluctuated much. I had a small bucket, and changed just the filter to see if the anti drain back went weak, but....it did not change anything. Is it possible the oil had too much dilution?
Now for my observation. After about 3-3500 miles, the engine would drain back oil pressure after each shut off. As most engines have a slight knock after a fresh oil change for first start, this was doing it after every restart. Oil pressure when running however was about 45psi, and never fluctuated much. I had a small bucket, and changed just the filter to see if the anti drain back went weak, but....it did not change anything. Is it possible the oil had too much dilution?
