I have an 07 A3 quattro SLine which I have had for a year. It has always used a small amount of coolant which in the manual says is usual, however over the last few weeks it has started using a bit more and i am having to add small amounts every few days if I do more mileage. I have had a pressure test done and nothing seemed to leak and no water in the footwells so dont think it its the heater matrix. Have been topping up with water so would that make a difference ? Any other ideas of what it could be.

 

Check for some leakage around the plastic reservoirs on the radiator when it hot. G12 will leave an orange/red solid residue where it leaks. These radiators today are crimped together and after thousands of heating up and expanding and cooling off and contracting, the crimps simply open up over time and cannot hold the pressure like they did when new. It is possible to re-crimp them and I've done it a couple of times on radiators that are EASY to remove. However, it's just a short term fix as they will open back up in just a few months.

The radiator on my A8 is leaking a bit around the reservoir on the passenger side. Just enough to have to add a bit every couple of weeks but never enough to make it all the way to the ground to indicate a leak. But I can see just a little moisture and some of that orange/red deposit where it's leaking. It only leaks when it's hot so. I'm putting off as long as I can. The radiator for my car is $500+ and I'll have to drop the front fascia to remove and replace it. I do keep a close eye on it though. I'm probably going to break down and order the radiator in a couple of weeks and have it on hand just in case it does decide to pop..

 

thanks, I'll have a look at that.