I think you'll be fine for the winter although if the engine consumes any oil you could top up with straight Delvac 0W-40.
Adding as little as 250mls will bump you into the light 0W-30 category.
Next OCI (for summer use) if you want to play it more conservatively go for 2 litres of Delvac for a 60/40 blend.
That will give you a 0W-30 with a 3.1cP HTHSV and 203 VI.
Still lighter on start-up than a 5W-20 at room temperature and over 20% lighter at OC.
Adding as little as 250mls will bump you into the light 0W-30 category.
Next OCI (for summer use) if you want to play it more conservatively go for 2 litres of Delvac for a 60/40 blend.
That will give you a 0W-30 with a 3.1cP HTHSV and 203 VI.
Still lighter on start-up than a 5W-20 at room temperature and over 20% lighter at OC.