As long as you don't have freezing weather, running without coolant for one or 2 days is ok. RO = reverse osmosis.
If the engine is not running at operating temperature, sludge in system would be stuck and won't be cleared by normal flushing.
When flushing, always use clean water to final flush before adding coolant. Mixing of different brands of coolant can result in clogging of the cooling system, especially the radiator core so you have to flush clean and also after using flushing agents.
Wednesday, June 27th, 2012 AT 8:42 PM