Dip Stick and Thermostat housing

The yellow knob is the oil dip stick, the dip stick circular container is the oil filler for engine top up.
To the right of the dip stick is the water coolant thermostat housing. The wrinkled cable top and bottom of it, are the senders for the water temperature gauge and boiling lamp indicator.
The white trough, above the yellow dip stick, is placed in this position to protect the black plastic pipe which was wearing through with engine vibration. A permanent solution will be incorporated soon!
It is recommended to change the oil at 6months what ever the mileage. Mainly because the Turbo takes oil from the engine to lubricate it. Old oil wont do this effectively causing it's inherent problems.

The pipe marked 'Turbo Feed' should be checked. Take off and clean inner bore.
This pipe taps off turbo pressure and feeds to the valve over the diesel pump. When the throttle is pressed hard the turbo pressure lifts the valve and feeds more diesel into the pump during the extra throttle function.

 The 'Coolant Temperature Switch' has these markings. Useful if replacement required.  01 - 22K5 - 401044 - JAEGER - PAR

Coolant Temperature Switch which provides a RED light on the dash during fault conditions

Coolant Temperature Switch which provides a RED light on the dash during fault conditions.
Located above the Thermostat housing. 
This monitor is either on or Off.
Normal==OFF
Fault==Lamp ON

Coolant Temperature Switch

I have found to remove the device requires a straight through 19 mm box spanner.

The Dash Gauge coolant monitor is variable.