my car has been running for 2 years since i got it with just plain water coolant. so far ok naman. always normal operating temperature. kaya lang you have to check ur radiator every now and then para magdagdag ng water kase parang nag e evaporate din sya ng konti. and 1 thing i notice is yung parang residue nan nakadikit sa loob ng radiator. pagtagal tagal siguro mababarahan nun mga butas kaya kailangan ipa overhaul ung radiator. i think its a good thing to add 50% coolant para maganda ang maintenance ng radiator natin.