If i had never used slick50 and read that i would stay well away However my 300TDI Discovery had 80,000 miles on it when i bought it. When i sold it, it was just short of 200,000 miles on it and i never had any engine problems apart from leak in water pump caused overheating had head skimed and fitted back on. I had to replace gear box, sills, floor and many more things but nothing regarding the engine. A friend of mine now ownes it and has done for 8 months and it still runs perfect. I wish i had soaked the whole car in slick 50. This is my experience i'm sure many people will slate slick 50 but i have no complaints and i now have it in my 2004 TD5 with 43,000 miles on it. Just thought i would have my 2 bobs worth.