I have a bmw 318 auto 1999 m43 engine I cant seem to find any instructions to change the transmission oil any instructions i find is a totally different gearbox any help would be much appreciated, Iam experiencing a strange noise at 30 to 40 mph its like the noise you would get if dropping down to low a gear on a manual transmission car but its very faint and sounds as if its coming from the rear any info would be great.