i have a 2wd saff and its stage 3 (just set up 2 weeks ago)i have 5~40 fully synthetic oil which i now know is wrong and im changing it at the weekend, when the car is fired up on a morning the is a whirr, it is not the diff or gearbox as i have checked them,i am almost certain its the turbo it does it when the boost reads -5 -0 psi then goes off.it only does it a couple of times then is fine.do you think it is the oil? plese help as it is bugging me thanx rs 4 ever