Vauxhall Astra Owner's Manual page 254

Inform ation on AC EA oil grade
cla ssific ation
The Association d es Constructeurs
Européens d'Automobiles classifies engine
oils according to their perform anc e
(quality).
Ea ch class is identified by letters and
numbers, e.g. A3:
The letter indicates the field of application:
A = Petrol eng ines in passenger cars
B = Diesel engines in passenger cars
E = Diesel engines in trucks
The number shows the quality in
numerically ascending order:
252
Informat ion on SAE oil vi sc osit y
Engine a nd transmission oils are grouped
in SAE classes b y the S oc iety of Automotive
Engineers b ased on their v iscosity.
Viscosity is the measure of interna l friction
of the oil in flux , dependent on its
temperature.
The SAE classification does not provide
information on the quality of the oil; it
merely indicates the range of application
of the oil dependent on the outside
temperature – see diagram.
The first number indicates v iscosity at low
temperatures (cold sta rt behaviour). The
second num ber indicates visc osity a t hig h
temperatures.
Do not sw itch to a different viscosity in the
event of brief temp erature fluctuations.
A = S AE classes for petrol eng ines
B = S AE classes for diesel engines