Lubricating Oil - Vetus M4.55 Operation Manual

9 Operating media
Engine oil
Lubricating oils are specified by perform-
ance and quality classes. It is usual for the
specifications to be indicated according to
the API (American Petroleum Institute).
Acceptable API oils : CF, CF-4, CI-4
Only use oil of a recognised brand to lubri-
cate the engine. The choice of a correct oil
guarantees that the engine starts easily,
because an oil film remains on the cylinder
walls and bearing surfaces. The friction is
low and so the starting rpm necessary for
a dependable start can be achieved with a
lower starting torque. An incorrect choice
of oil can lead to a thickened oil layer on
the cylinder walls and bearing surfaces.
This can in turn lead to higher frictional
resistance and more effort, which forms
a hindrance to reaching the starting rpm
required for a dependable start, and this
results in a reduced lifespan.
84
Recommended lubricating oil vis-
cosity
There are two important considerations
when it comes to ambient temperature in
order to achieve satisfactory engine per-
formance.
• the possibility to turn the engine over
quickly enough to make an easy start
possible and
• adequate lubrication of internal wear
surfaces during starting and warming
up.
By making the right choice of lubricating
oil these requirements can be met. The
recommended oil viscosity is shown in the
overview below:
Recommended lubricating oil viscosity
-30
Starting tempera-
(-22)
ture °C (deg F)

Lubricating oil

viscosity
Because the viscosity (runniness) of lubri-
cating oil varies with temperature, the
ambient temperature in which the engine
is started determines the choice of viscos-
ity class (SAE class).
To avoid having to change the oil for differ-
ent seasons we recommend SAE 15W-40
all-season motor oil.
For example:
Vetus Marine Diesel Engine Oil 15 W-40
Shell Nautilus Premium Inboard 15W-40
For oil capacity see p. 81.
-20 -10 0 10
(-4) (14) (32) (50)
SAE15W-40
SAE10W30
SAE5W-20
lubricating oil
20 30 40
(68) (86) (104)
SAE30
SAE40