synthetic lubricants for 1,6

[Ed Levin]

Of course, you're quite right that at operating temperature there's no difference between 5W40 and 10W40--it's the 40 that matters.

As I understand it (and I am also no expert), the real difference is that when the engine is shut down, a 10W- leaves a thicker film on the components than a 5W-. A thicker film will protect the components better and reduce wear on start-up, but will be more difficult to start at low ambient temperatures. Low ambient temperature is not an issue for me (in southern California), so I will probably opt for the greater protection.