Don't care what kind of oil it is. Using the same engine oil for 25 thousand miles is stupid. It's likely problems won't appear for awhile, maybe not until after you've sold the truck. Oil changes are cheap. Drain the old contaminated stuff out and get on regular routine maintenance intervals. It's not that I don't believe in synthetics, I use them in gear boxs & final drives & stuff. On a side note a buddy of mine developed a bad rear main oil leak on his 50K mile PSD within a month of switching to Amsoil. Coinsidence?