Just picked up 5 quarts of the authentic German Castrol 0W-30 at my local Autozone. There was only 1 quart left on the shelf! Couldn't believe I found it!!!! I plan on running it this winter. I normally run Mobil 1 0W-30 during the winter. Some questions for the board: Which oil is better in your opinion? Mobil 1 has kept my engine EXTREMELY clean. Will the German Castrol do the same? Does the German Castrol have esters in it? Are esters superior to PAO's? Will I be able to run the German Castrol for the conservative drain inetrval of aprox. 6K? Can I run the German Castrol 0W-30 year round? My owners manual calls for 5W-30 (94 Honda Accord EX 93K on it)in all four seasons. What are your experiences with the German Castrol? Thank you for your help!!