The thing to remember with using the cheaper coolants is that they arent going to cause problems short term,its over time that good quality coolants stand out.Good quality coolant will stop corrosion and electrolysis. Electrolysis is when the aluminium from the radiator (or from any alloy cooling system parts for that matter) is eaten away by the coolant and deposited onto the engine block by way of the electrolysis process (happens mostly when plain water or diluted or old coolant is used over time)Welch plugs are also one of the first things to go usually....Cheaper quality coolants are probably closer to the dearer coolants when it comes to their anti freeze-anti boil properties, if they are mixed at the correct ratios.Its mainly the corrosion side of things though where they fall behind..A lot of people dont mix coolant to the correct ratio to top up the radiator.A lot of people just add a bit of water thinking that bit of water wont make much difference.But it does.To keep the coolant at the correct ratio,always top up with the proper mix of coolant and water.I carry a 5 litre old coolant bottle with the coolant in it mixed ready to go when I need to top it up,which is hardly ever anyway.