hey, i recently bought a defender 90 with a 200tdi engine in it. it was a bit smokey when i bought it but i though that was because the turbo was had a leak and was leaking oil, after buyign a new turbo, changind oil and filters, it still producing black smoke(more than it should). also it is spitting oli out from dip stick and white smoke + oil coming from crank breather. is it teh piston rings as i thouhg?