I changed out the FF at 935 km (560 miles). FWIW (and probly not much) the OLM read 93% and the oil coming out was pitch black; mostly city driving. As replacement I used Q Horsepower 5W30 (great sale price of $22 CDN for 4.4 L/4.65 qrts). And again the filter is the AC Delco PF48. So with these #s when would you change out this fill?