Vauxhall ASTRA Owner's Manual page 294

Check the underbody after washing and
have it waxed if necessary. Before the start
of the cold weather season, check the PVC
coating and protective wax coating. Have
them restored to perfect condition if
necessary.
Caution – commercially available bitumen/
rubber materials can damage the PVC
coating. We recommend that you have
underbody work carried out by a
workshop, who knows the prescribed
materials and has experience in the use
thereof.
The underbody should be washed
following the end of the cold weather
season to remove any dirt adhering to the
underbody since this may also contain salt.
Check protective wax coating and, if
necessary, have it restored to perfect
condition.
Astra TwinTop
Treat all seals, e. g. on the roof and
windscreen frame, with silicone oil from
time to time. Good contact between the
fine rubber lips and the sealing surfaces
prevents leaks and reduces clamping
forces.
The roof can be held in an intermediate
position for about 9 minutes by releasing
the operating switch in order to clean roof
spaces.
Intermediate roof position for cleaning –
see page 58.
Do not use high-pressure jet cleaners.
Self-help, vehicle care 293