I just had the PTU flush performed at my local dealer and in fact it certainly needed it at 33k,the fluid was black and needed to be flushed out a couple times slowely and the procedure took roughly two hours to have done,he also found a leak on one of the DP and fixed that issue,the only downside was that only Mobil one 75w-140 was only available in such short notice,pic's below as promised and BTW pic of the ptu temp sensor below. Z