It could be the crack (coolant) pipe, or thermostat housing leak. Have something that knows about the engine look for signs of coolant leak. Unless your oil is foaming, then it sounds like a head gasket leak.
G12 You have to get it form the dealer
There are only two acceptable brands of coolant for your car.The first is "official VW G12." This is pink and comes from a Volkswagen dealer. Volkswagen buys it from the German chemical company Pentosin.If you don't have a VW dealer in your area, or you don't like the one you have, the same product is sold as "Pentofrost SF." NAPA stores should have it; if yours doesn't keep it in stock, they'll special order it for you.
Volkswagen.
There are many Volkswagen dealers that sell new cars that are based in Seattle. Examples include Bellevue Volkswagen and Auburn Volkswagen and Larson Volkswagen.
Have you tried a Volkswagen dealer.
I would believe that the best place to find information on Volkswagen parts would be from the Volkswagen company itself. You can also contact your local Volkswagen dealer to get information on their parts.
Dealer? Salvage Yard?
The best place to purchase a new or used Volkswagen is your local Volkswagen dealer. When buying used, they can offer certification and warranty that a regular dealer may not offer.
One can find a used Volkswagen Touran at a local Volkswagen dealer in the United Kingdom. Some Volkswagen dealerships in London, England are Dovercourt VW, Citygate and Alan Day Volkswagen.
Go to the Dealer!!!
ford premium gold coolant , also mask the dealer about the diesel coolant additive
The dealer.