For the last year i have been using Magnatex Castrol 10w40 in the car,I noticed there was a whistle to the turbo which was very pleasant to the extent i would mute the CD player sad i know,
Anyhow yesterday hada filter and oil change with 5w40 oil fully synth,
Today i noticed it was whistling like a song bird,Maybe is it because of the oil?
The car doesn't smoke and using minimal oil between monthly checks,
So any views?