Honda recommends that our cooling system be serviced every 8,000 miles. In the Service Manual, Honda shows how to inspect a cooling system. Basically it includes pressure testing a cooling system, and radiator cap. It also includes removing the reservoir tank, cleaning it, and inspecting the reservoir, and it's hoses.
Below is an example of why a cooling system inspection is important. It's been my experience, once a leak is found, most owners are not aware that they have a coolant leak. This particular Wing's cooling system was under a pressure test for over 2 hours, and still no coolant had dripped onto the floor. It's leak is slowly pooling into a rubber mat. Once the level fills the mat area high enough, it will then begin to drip off. Depending which way it drips, it may then pool into another area before finally hitting the floor. On GL1800s, all mats lay differently. Some leaks may pool, while others may instantly make a quick route to the floor. While being rode, the pool may instantly empty because of acceleration forces. The thing to remember is this, our Wings have over 42 hose clamps, any of which may cause a leak, and the owner may not even be aware of it. Unfortunately the only way to know if your Wing does not have a coolant leak is to constantly do cooling system services.
I would guess that 40-50% of the Wings that come in for a service have a coolant leak. The sad part about having a Wing service is this. Most service departments do not have the pressure tester and the adapters required to test for it.