On Alfa number 15
AO Platinum Member
Join Date: Dec 2005
Location: United Kingdom
It is meant to be run on 10w-60 to help cut oil consumption.
People coming to Alfa from other Marques didn't realise it was nessesary to check the oil every week.
This meant that many engines got run low on oil and it cost Alfa a fair bit in warranty claims.
Because a 10w-60 oil is thicker it tends not to burn off as quickly, however that also means that it is harder work for the oil pump to pump it around the engine.
The top of the engine is furthest from the pump and will tend to suffer first.
Also its optimum working temperature will be higher. It may never reach optimum temperature in road use in the UK, especially during the colder months. This won't do the engine much good as the effect is similar to using a thinner oil (Such as a 10w-40) and driving hard before the engine has warmed up.
You will never be cool driving a Vauxhall.