Lexus LS400 recommends Ethylene Glycol so I use either Preston or Peak All Makes and flush every 2-3 years with T-flush and city water, so far there is no problem after 270+k miles. Thermostat and water pump had been changed once several years ago. Honda S2000 still have OEM coolant, I'll flush it out in about 2-3 years and probably use Peak Global. MB E430 jut had new Zerex G-05 in it last summer and it will be in the engine for 5-6 years. Since coolant doesn't needed to be changed every year, I don't see a need to use cheap coolant in every engine. What if you need 2 gallons concentrate coolant and pay $20-30 a gallon every 4-5 years, is it too much ?