So, I bought a new Toyota Sienna in 2002. I knew about the sludge problem the engine had but was given assurances that the PCV had been enlarged and some mods were done to get better combustion of the gases.

I used Mobil 1 and new filters, mostly Toyota, but a Wix thrown in here and there. In July, at 112,000 miles, the engine sludged. Don't tell me that it is unlikely to sludge using synthetic.

Toyota replaced the block and paid the labor. I bought new Toyota timing belt, water pump, etc. So, whole new set up.

My question...why keep using Mobil 1?