Fleet Maintenance - 12

Engine oil basics

There are three basic ways to categorize engine
oils: by viscosity, or the oil's resistance to flow;
by the primary base stock, whether the oil is
mineral, synthetic, or a blend of both; and by
the performance level of the oil, how it protects
the engine, prevents wear, and protects against
heat, shear, and aeration.

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12 Fleet Maintenance | May 2019

Viscosity
The most common reference to oil most are familiar with is viscosity. This is denoted by numbers,
such as 10W-30 or 15W-40. The first number,
before the W, which stands for "winter," indicates the oil's viscosity at 0 degrees Fahrenheit.
The second number indicates the oil's viscosity at
212 degrees Fahrenheit. The larger the numbers,
the higher the viscosity.
Higher viscosity oils are heavier and typically
coat the engine better to provide more lubrication
and protection, but can become overly viscous in
colder climates. Lower viscosity oils work better
in cold weather and also provide improved fuel
efficiency, but can become too thin to properly coat
and protect engine components in hotter climates.
It is important to strike a balance depending
on the conditions under which the vehicle will be
operating, but the most important factor remains
the engine manufacturer's recommendation.
Diesel engines, particularly modern ones, are
designed to operate using specific oil viscosities
for optimum longevity and efficiency.
"For ages, 15W-40 was kind of considered the
diesel viscosity grade," says Dan Arcy, OEM technical manager for Shell Lubricants, a global lubricant supplier. "But as we started to move [to] lower
emission engines, starting in 2007 to 2010, a lot of
the engine manufacturers ... have switched over
to 10W-30s or 5W-30s."
Mineral oils, synthetics,
and synthetic blends
Engine oil is also categorized into four groups by
the natural gas and oil standards-setting organization, American Petroleum Institute (API). These
groups, labeled I through IV, describe different
levels of base oils, or base stocks, which lubricant
companies use to create specific engine oil formulations marketed to businesses and consumers.
"Group I is the most fundamental and historically the most common base oil in the traditional
mineral oil family," says Brian Humphrey, OEM
technical liaison for heavy duty at Petro-Canada,
a developer and producer of lubricants. "This is
measured by the amount of sulfur that remains in
the oil [after refinement] and its viscosity index."
The viscosity index is a measure of an oil's
change in viscosity versus temperature. The
higher the viscosity index, the less it changes
with temperature.
"Group I is the lowest," Humphrey says. "Group
II is slightly better on both of those properties: less
sulfur, higher viscosity index. Group III is the highest of traditional mineral oil qualities. And then
finally, group IV are oils that are assembled from
a singular type of chemistry molecule, the most
common of which is polyalphaolefin, or PAOs."
There is a Group V, which consists of all base
stocks not defined by any of the first four groups.
These are not used as base oils for engine oil, but
rather as an additive to other base oils.
In the U.S., Groups I and II are considered
mineral oils, while Groups III and IV are labeled
synthetic oils. Technically speaking, Group IV is
the only true synthetic, but Group III oils' properties are within specification to provide the performance of a synthetic.
"A full synthetic ... the base oil that's in it is not
something that's common or [occurs] in nature

Best practices
when switching
to CK-4 and FA-4
heavy duty
engine oils
API's Director of Product
Programs provides several
important measures fleets
can take to ease the transition
to the latest engine oils.
"With the creation of two diesel engine oil
categories a few years ago and with a growing
number of viscosities for diesel engines, shops
need to properly accommodate numerous oils,"
says Kevin Ferrick, API's director of product
programs. "Training technicians and service
people about each application is very important so that misapplications don't occur and
potentially result in expensive engine damage
and voided manufacturer warranties."
If a fleet hasn't done so already, replacing
CJ-4 with CK-4 oil is a relatively simple transition because CK-4 is backward compatible
and an improvement over CJ-4. Ferrick provides several important measures fleets can
take to ensure that diesel engine oils are
being installed and dispensed properly.
* Storage. Be sure to completely drain all
bulk tanks that will be receiving a new
oil. You can still carry CJ-4 oils in drums
if you want to keep some on-hand.
* Identification. Clearly mark all bulk
or packaged oil as appropriate for
API CJ-4, CK-4, and FA-4 oil.
* Dispensing. All dispensing equipment
should be properly labeled with product name, viscosity grade, and service
category to prevent misapplication.
* Education. Technicians should be
made aware of the changes to oil categories and requirements for each.
For any diesel oil, be sure to mark tanks, storage,
tools, etc. to avoid commingling different products and misapplication. Reassess your shop's
need for all the oils you stock and eliminate older
oils like CJ-4 which should no longer be necessary. Also, evaluate specific viscosity grades and
adjust inventory to ensure you stock the proper
supply of the most commonly used oils. If you
plan to make changes, set a specific date and
clearly communicate that information to staff.

- it's a designed base oil," Arcy explains. "The
synthetic blend is really just ... a mixture of
mineral oil and synthetics. A synthetic blend is
really kind of a combination, it's kind of midpoint.
You get some of the extra benefits of a synthetic,
but not all of them."

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