undercarriage BMW 330Ci COUPE 2001 E46 Owner's Manual

142n
Caring for your vehicleExterior finish To provide effective corrosion protec-
tion, multilayer paintwork is applied at
the factory. Cataphoretic immersion
priming techniques are supplemented
using special body-cavity protectants,
with the application of specially-devel-
oped and extensively tested materials.
A layer of flexible PVC is first applied to
the undercarriage. Following this, a
comprehensive undercoating treat-
ment with a wax-based protectant is
applied. Regular maintenance makes
an important contribution to maintaining
the safety and value of your vehicle.
Increasing awareness of the effects of
harmful environmental factors on
vehicle finishes have led paint and
vehicle manufacturers to initiate
ongoing programs designed to further
improve the durability of their finishes.
Despite this, environmental factors that
occur locally or regionally can have
negative effects on the finish of your
vehicle. Use the factors to determine
the frequency and extent of your efforts
to maintain the vehicle finish.Depending upon material and type of
impact (perforation of paint layer),
physical stresses from sand, road salt,
gravel, etc., can cause corrosion to
start extending beneath the finish,
starting at the point of impact.
Road dirt, tar spots, dead insects,
animal droppings (strong alkali effect)
and tree excretions (resins and pollen)
all contain substances capable of
causing damage when allowed to
remain on the finish of your vehicle for
any period of time. This includes spots,
etching, flaking, and separations in the
top coat.
In industrial areas, deposits of flue dust,
lime, oily soot, precipitation containing
sulfur-dioxide (acid rain) and other
environmental pollutants will damage
the vehicle's finish unless adequate
care is provided Ð even though this is
generally limited to the outside
horizontal surfaces.In coastal regions, high levels of atmo-
spheric salt and humidity promote
corrosion.
In tropical zones, temperatures of over
105 7 (+40 6) in the shade prevail, in
addition to heavy ultraviolet radiation
and high humidity. Under these condi-
tions, light paints can reach tempera-
tures of up to 175 7 (+80 6) and dark
paints up to 250 7 (+120 6).