[groar]

Originally Posted by 1.5Ldave

Are your findings with the car just started up or after its at operating temp? The lower weight oil should make a noticeable difference on start up because the it doesnt have to warm up as much to achieve its operating viscosity. I know an old van my parents used to have said in the manual to use different oil weights depending on winter or summer. At least thats the only reason that comes to mind, unless your air filter was really really really dirty.

When the car is at operating temp.
Is it possible a 10w oil isn't 100% synthetic ?
I heard the 5w can only be synthetic. The 5w used (8100 X Clean) is 100% synthetic : MOTUL

The air and diesel filter may also be a possibility, but it was the 6th maintenance and I never saw such a difference.

I plan to visit my mechanic when he is back from holidays to know more about it and see the difference between his 10w and 5w oils. He insisted on the fact the 5w is more expensive and it was 20% more expensive. It may be some magic with some additives in this oil, or some magic from new kind of filter, or...

Denis.