well the last month or two id say, when i start my truck in the morning it takes a about 15-20 seconds before i hear the turbo start to spool. now about 2-3 seconds after initial start i get oil pressure like normal and as soon as that used to happen i can hear the turbo come on. now after 20 seconds like i said there is a lil screatching sound then here comes the "jet" note from the exhaust. i change my oil 2500-3500 miles and use rotella for the most part and wix filter. i did use delo this past oil change but this symptom happend before i changed oil anyway. any thoughts???