I agree, yearly may be recommended by somebody somewhere but I bet there aren't more than a handful of people that actually do it. Mine gets flushed every time I do the brakes which is five to seven years.
1953 Chevrolet 3600 Fried Green T'mater (Vern) In the Stovebolt Gallery Caution: Political Statement Man who runs in front of car gets tired, man who runs behind car gets exhausted.