I renewed the coolant because it is something that should be done every 'X' amount of time, normally it is indicated every 2 years, but it largely depends on many engine operating conditions. In non-extreme climates and with 'normal' driving/use, the useful life of the coolant can be greatly extended (2>4 years).
We all know old engines that are more than 15 years old in which the coolant was never changed, even more years and they work relatively normally, but this cannot be done with current engines, the calibrated passages through which the coolant circulates are very narrow, and the materials of the engines are more sensitive so as not to go into further explanations. The coolant needs to be in perfect>good working condition at all times if you want to extend the life of the engine.
According to the repair manual, the coolant replacement procedure is very similar in almost all engines (with the original VAS tool, a vacuum system), and you must also take into account whether your engine requires a bleeding procedure. ODIS S tells you if it is necessary to bleed the cooling system on your engine. It is normally applied to diesel engines and I think in larger displacement engines with a
more complex cooling system.
Draining the coolant through the radiator is what the manual says, but it does not renew all the coolant in all the pipes, narrow passages, pumps, thermostats, etc... if you do not have the VAS vacuum system to achieve it.
If you renew the coolant through the return pipe that reaches the expansion tank, with the engine at operating temperature and idle, making the mechanical pump, the electric pump and the radiator fan work, you will be able to expel the 100% of the old coolant without having to drain it through the radiator pipes.
You have to keep some type of liquid in the expansion tank at all times while the old coolant is evacuated through the return pipe, either 'distilled water' to clean/flush the system or the new coolant, which will be responsible for expelling the old coolant.
'Never' use tap water, wine, beer, spirits, or other atrocities.
My Golf was not affected by the G13 and silicate bag problem, it did not have the silicate bag, which is indicated on the expansion tanks of the affected engines, but I changed the tank because it had the G13 icon drawn on the surface. Due to the bad reputation of the G13, it is better to get it out of the way to avoid confusion in case of repairs, sale of the vehicle, etc.
There are those who paint the expansion tank with a marker... in my most sincere and humble opinion, I think it is not the best for vehicles of 'very high international prestige'. All my respects and I understand everyone's conditions and needs.
My expansion tank now it is just the icon without any nomenclature, 'currently' the G12evo is the one indicated for all engines.
