BMW 540 I 1997 transmission service when?

According to the owner's manual of a 1997 BMW 540 I, the automatic transmission fluid and filter should be changed every 80,000 miles or 8 years of the first change, whichever comes first. For severe service, which includes frequent towing or driving in dusty or hot conditions, the interval should be halved to 40,000 miles or 4 years, whichever comes first.