In addition to the new tests, API CH-4 oils have
tougher limits for viscosity control in applications that
generate high soot. The oils also have improved
oxidation resistance. API CH-4 oils must pass an
additional test (piston deposit) for engines that use
aluminum pistons (single piece). Oil performance is
also established for engines that operate in areas
with high sulfur diesel fuel.
All these improvements allow the API CH-4 oil to
achieve optimum oil change intervals. API CH-4 oils
are recommended for use in extended oil change
intervals. API CH-4 oils are recommended for
conditions that demand a premium oil. Your Perkins
distributor has specific guidelines for optimizing oil
change intervals.
Some commercial oils that meet the API
classifications may require reduced oil change
intervals. To determine the oil change interval,
closely monitor the condition of the oil and perform a
wear metal analysis.
An oil specification that is above CH-4 is acceptable
for use in Perkins engines.
NOTICE
Failure to follow these oil recommendations can
cause shortened engine service life due to deposits
and/or excessive wear.
Total Base Number (TBN) and Fuel Sulfur
Levels for Diesel Engines
The Total Base Number (TBN) for an oil depends on
the fuel sulfur level. For engines that use distillate
fuel, the minimum TBN of the new oil must be 10
times the fuel sulfur level. The TBN is defined by
“ASTM D2896”. The minimum TBN of the oil is 5
regardless of fuel sulfur level. Illustration 35
demonstrates the TBN.
Illustration 35 g00799818
(Y) TBN by “ASTM D2896”
(X) Percentage of fuel sulfur by weight
(1) TBN of new oil
(2) Change the oil when the TBN deteriorates to 50 percent of the
original TBN.
Use the following guidelines for fuel sulfur levels that
exceed 1.5 percent:
• Choose an oil with the highest TBN that meets
one of these classifications: API CH-4 and API CI-
4.
• Reduce the oil change interval. Base the oil
change interval on the oil analysis. Ensure that the
oil analysis includes the condition of the oil and a
wear metal analysis.
Excessive piston deposits can be produced by an oil
with a high TBN. These deposits can lead to a loss of
control of the oil consumption and to the polishing of
the cylinder bore.
NOTICE
Operating diesel engines with fuel sulphur levels over
0.5 percent will require shortened oil change intervals
in order to help maintain adequate wear protection.
Table 38
Percentage of Sulfur in the
fuel
Oil change interval
Lower than 0.5 Normal
0.5 to 1.0 0.75 of normal
Greater than 1.0 0.50 of normal
Lubricant Viscosity Recommendations
for Direct Injection (DI) Diesel Engines
The correct SAE viscosity grade of oil is determined
by the minimum ambient temperature during cold
engine start-up, and the maximum ambient
temperature during engine operation.
Refer to illustration36 (minimum temperature) to
determine the required oil viscosity for starting a cold
engine.
Refer to illustration 36 (maximum temperature) to
select the oil viscosity for engine operation at the
highest ambient temperature that is anticipated.
Generally, use the highest oil viscosity that is
available to meet the requirement for the temperature
at start-up.
SEBU8311-09
55
Maintenance Section
Fluid Recommendations
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