there is a problem with the 05/06 magnesium clutch case that you really need to check if you own one.. seems Suzuki put these light weight cases on and didn't think about which coolant to use.. what they put in them is eatting the case away and can cause coolant to get in the oil.. very nasty things happen then.. if you own one drain the coolant and take the water pump loose.. then turn it 90 deg. and look at the water hole in case.. im sure you will be as upset as i was.. this is not a one time happening.. this is being passed on to suzuki/kaw. owners on the net and bye word of mouth..
first tell tale sign is the coolant in water bottle changing color.. thats metal in your coolant.. and radiator and every where else..
if you can post this where owners can find it and pray for a recall on these cases.. a new one is 180 bucks plus a proper coolant to stop it from happining again..
Z400central has a tread with pics from about 60 differant bikes this has happened to
hope this saves a few engines..