well i took the feed line off the turbo and turned the car over an the oil came out fine, i changed the oil but not the oil filter when i did the turbo, the oil came out really dark an sludgy is this cause i didnt change the filter, i didnt really want to change it cause ive got it booked in for a service in 2 wks an there gone do it for free. i spoke to a mate today an he said that it could be over boasting thats while it might b making that whistle noise, he said the best way to check is to get a boast gauge, dont i have to alter the accuator to change the boast, which means the turbos got to come out, if it is over boasting what do i need to do???