I have a 2010 Camry with 105,000. Bought at 85k and was no history of transmission maintenance. My local repair shop changed fluid (2 quarts) at 90k with the factory WS fluid. They recommend staying with that fluid forever, and said that the fluid they drained out didn't look bad at all. Hope their idea of not bad is close to mine. If I'm interested in longest life, should I keep with WS fluid or start the change to synthetic now. Am planning to change fluid again this next week. One concern I have and a main reason for another change of fluid is that even after the first change, on very, very steep grades, it slips a bit once in a while. Am hoping another change (with whatever fluid) will help with that. If syn is the rec, do I go with Redline D6 or Amsoil Low Viscosity? All input will be much appreciated. My local shop strongly believes I should stick with Toyota WS fluid and are pretty uncomfortable putting anything else in. I generally trust these guys, but am still interested in what people here think about this. Transmission runs and shifts good with exception of already noted extremely occasional slip on a very, very steep grade at low speed.