BX aircon question

[DLM]

Petrol BXs with aircon have a different sump and, according to the drivers's book, take half-a-litre less oil . There's no such note for diesels.
(1) Do aircon diesels have a different sump and smaller oil capacity?
(2) What is the reason for the smaller capacity anyway?

[tomsheppard]

The aircon sump is alloy, hence thicker so it carries less. Should be a straight swap- I hope!