Volvo S60 T5
I put some slick 50 with P.T.F.E (Teflon) in my motor the other day, being sceptical about that sort of stuff working, thought I would give it a go.
It works, Im shocked. The car is much better, less engine noise, flat spot I had in the mornings has gone, and it pulls much better now, sounds much better when you rag the engine now no harsh sounds.
Give it a go.