I've got ~4500 miles on this oil change, about 3 months worth from a cross country sight seeing journey. Mostly 2k rpm 10 hours a day. Very little short trip drivig before and since Not yet 1 full quart of make up oil, which was PP 5w-30 SN d1g2. 5 quart sump capacity, FU XG8A filter. Rebuilt LA 318 engine with ~50k miles on it. Oil color means little, but it is fairly dark brown. Engine is clean, M1 oils for the last 10+ years. This oil made my engine significantly quieter than m1 oils. Oil pressure hot at same rpm is same as at mile 25 of this oci. Have the 2500+ mile return journey soon along I-10. I think this oil should be fine in this engine for 7500 miles. I am not sending off a sample to be tested as it would cost more than simply dumping it and I would not get results before leaving anyway. How long can PP 10w-30 be pushed in such an engine in mostly highway driving mileage? Opinions?