Castrol CRB Viscous is a old 25W-50 CC rated oil, till few years back it was sold here in India, quite popular with the taxi crowd due to its lowered consumption, the oil gets thick quite quickly once inside the engine.

For you I would suggest Delo 400 or Delvac MX, both of which are freely available in SA.

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99 Gurkha with OM616 IDI turbo

2015 Gurkha with OM616 DI turbo

2014 Rexton W with OM612 VGT