Just recently purchased a B7300 with 850 hours. Everything checks out except I don't see any fluid in the radiator reservior tank and when I open the radiator cap I don't see any fluid there either. I want to flush it out and start fresh but want to get some work in today and tomorrow before doing so (need to beat the rain). Can I just top off with water in both places or do I add 50/50 antifreeze? Was reading on another site about not wanting to mix antifreezes and you can't just go by color alone. So, should I just top off with water before I flush and clean soon or is it ok to use the standard green 50/50 without knowing what was in there before? FWIW, and yes I know stupid, I used the tractor two days ago for about 3 hours running a brush cutter without any problem or warning (may have been lucky). Thanks