I have had the problem with smoke at low speeds, on my 2.5TDI A6, that has been discussed on previous threads. Ended up with oil on both side of the turbo and the trurbo wrecked. Have fitted a new turbo from Turbo Technics (very helpful & reasonably priced) changed breather, cleaned oil and breater pipes, new oil and filter. After running the engine for a few minutes the oil warning light came on - anybody any ideas?