The recommended engine oil for the Biturbo (including Shamal, I assume) was AGIP Sint 2000 10W40.
Ferrari recommended this oil for their cars, including F40. After they switched the oil company to Shell, they recommended Shell HELIX Ultra 5W40. Not only for their new cars but also for older ones.
When Maserati was bought by FIAT, they switched to Petronas because FIAT used to use them. Petronas provided Selenia Racing 10W60.
When Maserati started to use Ferrari build engines, they started to use Shell HELIX Ultra 5W40, just like Ferrari. However, in 2018, they started to use Shell Helix Ultra 10W60 for the same engines.
Shell and Maserati are introducing a brand new co-branded motor oil known as Shell Helix Ultra Maserati 10W-60 - the only recommended on all Maserati’s 2018 models across the globe equipped with the V6 Gasoline engine. This new product follows the previous Shell Helix Ultra Maserati 5W-40 for...
www.shell.com