What is the best kind of trans fluid should I use in a kawasaki kx 80?

Fluid looks milkey, I need to change it but I'm not sure what is the best fluid to use,

Use what your owners manual recommends.

That milky look is homogenized oil/water.You might wanna>warm up engine>drain drain transmission,,let it sit a several minutes draining.>put a whole quart of ATF(Automatic Trans Fluid) which is overfilled.>ride it GENTLY a few minutes>Drain the ATF,,,let it drain a few minutes>If by chance it's still milky,,,Do it again---yeah,it's a nuisance to do it twice.But it's easier than changing trans shaft bearings in a couple months.Refill with proper level of whatever trans oil you're gonna run.I use ATF in most wet-clutch gearboxes,like your KX.

You can use a regular motor oil in the tranny or one of the special racing oils from Kawasaki, Bel-Ray, etc. The racing oils are made to withstand the abuse your clutch and gears take under racing conditions. They cost a bit more, but protect better.IMPORTANT. If you have milky oil then you have water in your tranny. You either rode in very deep water or your water pump seal is leaking coolant into the tranny. This will cause all sorts of bearing problems. Drain the fill the tranny, run the bike and repeat. If you still see the white death then plan on replacing the seal. It's a common thing with water cooled bikes.