Now about a 6 months ago on Opie Oils recommendations I changed from a 5w30 Ford spec oil to a 0w30 fully synthetic A5/B5 oil.

Now I noticed much faster cranking when cold, the oil light goes out quicker, the car is quieter and the car is much more responsive when cold.
Not only that I found it improved my economy by around 10%.

A few days ago on the TalkFord forum someone who has said he works in a Ford engine testing facility told me that it will damage my engine long term because the oil pressures will be out.

Now my understanding was the first figure before the 'w' is the cold viscosity. The latter number related to the hot viscosity. Therefore when up to temperature the 0w30 oil should be the same to the 5w30 oil.
That means the only time the oil is genuinely thinner is when the engine is cold.

Now this forum is much better when it comes to this sort of thing so would like your opinions on weather or not it's doing my engine any good.

Bailes.

 

In my experience of testing engines, unless you run oil temps I'm excess of 140degC (which you won't), then you'd have to be trying very hard to damage anything