spk2000, did you take notice of the bottom of the ST synthetic you used, and if it had WPP stamped on it? Because Walmart has different companies making their ST oil, depending on the area, perhaps you used the ST synthetic that wasn't made by WPP?
Originally Posted By: spk2000
Guess I wasn't very clear that i have had no sludge issues at all using Mobil1, PU or Amsoil. I tried the ST sythetic and noticed sludge inside the crankcase on visual inspection. I do run extended intervals usually over 10,000 miles and decided to try the ST just to try it. I have never had this with the other 3 brands that I typically use. I know it is not very scientific and just 1 observation but it was enough for me to steer away from it. Just wondered if anyone else has experienced this as well.