Hi, after in the operating instructions of my S40 2.4i MY2005 the suitable coolant is not mentioned with any word, let’s ask the forum, what is heard there ? Background is: At the moment the water in the compensation tank is unfortunately absolutely pitch black. I want to rinse the whole system with water soon and then fill it again, to check whether the water will color again black. It could be due to the cylinder head seal, however, speaks against that there is no bubble formation in the compensation tank with running engine and also that there is no oil film on the liquid. – Therefore it may have been due to the extreme short distance operation in the last years. Long speech short sense: What for a frost protection remedy belongs in an S40 II 2.4i (MY 2005) ? PS: Have already experience with the change, since I have changed the complete cooler on my passat due to leaking itself.