oil type BMW 540I SEDAN 2001 Owners Manual

172nCaring for your car
Exterior 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 impor-
tant contribution to maintaining the
safety and value of your vehicle.
Increasing awareness of the effects of
harmful environmental factors on vehi-
cle finishes have led paint and vehicle
manufacturers to initiate ongoing pro-
grams 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. These
should guide you in determining the fre-
quency and extent of your efforts to
maintain the vehicle finish. Depending upon material and type of
impact (perforation of paint layer), phys-
ical stresses from sand, road salt,
gravel, etc., can cause corrosion to
start extending beneath the finish, start-
ing at the point of impact.
Road dirt, tar spots, dead insects, ani-
mal 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 (spots, etching, flaking, separation
in the top coat).
In industrial areas, deposits from fly
ash, lime, oil deposits, sulfur-dioxide in
precipitation (acid rain) and other envi-
ronmental pollutants will all damage the
surface of the vehicle unless adequate
protection is provided.
In coastal regions, high levels of
atmospheric 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 those circum-
stances, light exterior finishes reach
temperatures of up to 175 7 (80 6)
and dark finishes up to 250 7 (120 6).