Is it safe to use a power steering stop leak product, or is this likely to cause problems long term? I have a small leak on the rack and this had been recommended, but also heard that it is not recommended for as it is not mineral oil based, which is a requirement of the VW, and that it that the swelling of the seals doesn't have an end point, which means that the long term effect is more leaks from more areas. How have others got on with these products.