Just a quick question. But I've been working my way through a complete fluid change and the last item on the list is coolant. Can anyone tell me why we change out the coolant on a regular basis? I live in a moderate climate and I don't think I've ever changed out the coolant on my car except as on a need be basis which hasn't happened in quite some time.

Just wondering? So tell me some REAL stories of all the terrible things that happen when you don't. I need to scare myself into doing it. Just spent three days replacing brake pads and fluids. Or at least pumping in some new brake fluid.

I don't change mine - I just top it up when needed. Even worse, I frequently don't even bother with coolant because I live in a soft water area, so no limestone to clog the system up. Yeah, the water does turn an ugly shade of peat brown eventually, but I can't see it so I don't worry about it

When I bought the last lot of coolant off BMW I was surprised to find it is now lifetime coolant.  Previously I used to change BMW coolant every 2 years, then I found Castrol coolant test strips and after 4 years the coolant was still testing  fine. I just went out and tested the coolant and it tested at the top end of both scales so that makes it 5 years on BMW coolant and distilled water mix.   Note I believe my brick has only ever had BMW coolant and there have never been any signs of corrosion or discolouration.
Regards Martin.

I use Peak Long Life coolant and change it at 5 year intervals.  It gives me something to do when I can't ride.  

If you have never changed the coolant, you have no idea of what it is, how long it's been in the engine, and if it was mixed with hard water.  For that reason I would just do the change and maybe a flush to make sure the system is working at peak efficiency.  When riding in hot weather you want to have the system working as well as possible.

Keep in mind that the reason for changing is that the anti-corrosion additives "wear out" over time in older coolants.  They are needed to prevent corrosion from making holes in the aluminum passages in the radiator.

Note: even if you have soft water, it's best to use distilled water with the coolant in a 60/40 water/coolant mix.