Joining this very late. I have a 2017 4/4 Sigma 1.6 and the handbook that came with it clearly suggests the following oil options:
SAE 5W30 semi synthetic
SAE 4W40 fully synthetic
SAE 5W40 Mineral oil
I believe the Sigma engine that Morgan use may not be a standard Sigma ( the label on the engine under "special equipment" states" Power Torque Order E4371- FCS Quote 2016-2295").
Would be interested in people's thoughts
