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Two-stroke oil (also referred to as two-cycle oil, 2-cycle oil, 2T oil, or 2-stroke oil) is a special type of
motor oil
Motor oil, engine oil, or engine lubricant is any one of various substances used for the lubrication of internal combustion engines. They typically consist of base oils enhanced with various additives, particularly antiwear additives, deterg ...
intended for use in
crankcase compression two-stroke engine
In a piston engine, the crankcase is the housing that surrounds the crankshaft. In most modern engines, the crankcase is integrated into the engine block.
Two-stroke engines typically use a crankcase-compression design, resulting in the fuel ...
s, typical of small
gasoline
Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic co ...
-powered engines.
Use
Unlike a four-stroke engine, the crankcase of which is closed except for its
ventilation system, a
two-stroke engine
A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a power cycle with two strokes (up and down movements) of the piston during one power cycle, this power cycle being completed in one revolution of t ...
uses the crankcase as part of the
induction
Induction, Inducible or Inductive may refer to:
Biology and medicine
* Labor induction (birth/pregnancy)
* Induction chemotherapy, in medicine
* Induced stem cells, stem cells derived from somatic, reproductive, pluripotent or other cell t ...
tract, so oil must be mixed with
gasoline
Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic co ...
to be distributed throughout the engine for
lubrication
Lubrication is the process or technique of using a lubricant to reduce friction and wear and tear in a contact between two surfaces. The study of lubrication is a discipline in the field of tribology.
Lubrication mechanisms such as fluid-lubric ...
. The resultant mix is referred to as premix or petroil. The oil is ultimately burned along with the fuel as a
total-loss oiling system
A total-loss oiling system is an engine lubrication system whereby oil is introduced into the engine, and then either burned or ejected overboard. Now rare in four-stroke engines, total loss oiling is still used in many two-stroke engines.
Stea ...
. That results in increased
exhaust emissions, sometimes with excess smoke and/or a distinctive odor.
The oil-base stock can be
petroleum
Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...
,
castor oil
Castor oil is a vegetable oil pressed from castor beans.
It is a colourless or pale yellow liquid with a distinct taste and odor. Its boiling point is and its density is 0.961 g/cm3. It includes a mixture of triglycerides in which about ...
,
semi-synthetic
Semisynthesis, or partial chemical synthesis, is a type of chemical synthesis that uses chemical compounds isolated from natural sources (such as microbial cell cultures or plant material) as the starting materials to produce novel compounds with ...
or
synthetic oil
Synthetic oil is a lubricant consisting of chemical compounds that are artificially modified or synthesised. Synthetic lubricants can be manufactured using chemically modified petroleum components rather than whole crude oil, but can also be syn ...
, and is mixed (or metered by injection) with petrol/gasoline at a volumetric fuel-to-oil ratio ranging from 16:1 to as low as 100:1. To avoid high emissions and oily deposits on
spark plug
A spark plug (sometimes, in British English, a sparking plug, and, colloquially, a plug) is a device for delivering electric current from an ignition system to the combustion chamber of a spark-ignition engine to ignite the compressed fuel/air ...
s, modern two-strokes, particularly
small engine
A small engine is the general term for a wide range of small-displacement, low-powered internal combustion engines used to power lawn mowers, generators, concrete mixers and many other machines that require independent power sources. These engin ...
s powering such items as garden equipment and chainsaws, may now require a synthetic oil, and can suffer from oiling problems otherwise.
Engine
original equipment manufacturer
An original equipment manufacturer (OEM) is generally perceived as a company that produces non-aftermarket parts and equipment that may be marketed by another manufacturer. It is a common industry term recognized and used by many professional or ...
s (OEMs) introduced pre-injection systems (sometimes known as "auto-lube") to engines to operate from a 32:1 to 100:1 ratio. Oils must meet or exceed the following typical specifications: TC-W3® (NMMA),
API-TC
API TC is a certification for two-stroke oils, awarded by the American Petroleum Institute. It is given after the product passes through stringent tests that determine the level of detergent performance, dispersion, and anti-oxidation. It is th ...
,
JASO FC Jaso or JASO may refer to:
* Jaso State, a princely state in British India
* Japanese Automotive Standards Organization (JASO), an organization that sets automotive standards in Japan
** JASO T904, a quality classification standard of four stroke mo ...
, ISO-L-EGC.
The relevant difference between regular lubricating oil and two-stroke oil is that the latter must have a much lower ash content, to minimize deposits that tend to form if ash is present in the oil when it is burned in the engine's combustion chamber. Additionally, a non-2T-specific oil can turn to gum in a matter of days if mixed with gasoline and not immediately consumed. Another important factor is that four-stroke engines have a different requirement for "stickiness" than do two-strokes.
Since the 1980s, different types of two-stroke oil have been developed for specialized uses, such as outboard motor two-strokes, as well as the more standard auto lube (motorcycle) two-stroke oil. As a rule of thumb, it will be stated somewhere on the printed label of most containers of oil available commercially, that it is compatible with "Autolube" or injector pumps. Those oils tend to have the consistency of liquid dish soap if shaken. A more viscous oil cannot reliably be passed through an injection system, although a premix can be used on either type.
"Racing" oil or castor-based does offer excellent lubrication, at the expense of premature coking. The average moped/scooter/trail rider will not achieve an appreciable increase in performance and will require very frequent teardowns.
Additive ingredients
Additives for two-stroke oils fall into several general categories: Detergent/Dispersants, Antiwear agents,
Biodegradability
Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. It is generally assumed to be a natural process, which differentiates it from composting. Composting is a human-driven process in which biodegradati ...
components and antioxidants (Zinc compounds). Some of the higher quality include a fuel stabilizer as well.
Standards
The current international standard (ISO 13738) for two-stroke gasoline engine oil evolved from
JASO M345 Jaso or JASO may refer to:
* Jaso State, a princely state in British India
* Japanese Automotive Standards Organization (JASO), an organization that sets automotive standards in Japan
** JASO T904, a quality classification standard of four stroke mo ...
, which were grades intended to exceed
API-TC
API TC is a certification for two-stroke oils, awarded by the American Petroleum Institute. It is given after the product passes through stringent tests that determine the level of detergent performance, dispersion, and anti-oxidation. It is th ...
. Grades include:
[https://www.oilspecifications.org/iso_2t.php]
* JASO FA is abandoned. It is not put in ISO.
* JASO FB evolved into ISO L-EGB, with additional test for piston cleanliness.
* JASO FC evolved into ISO L-EGC, with additional test for piston cleanliness.
* JASO FD evolved into ISO L-EGD, with additional test for piston cleanliness and detergent effect.
The
National Marine Manufacturers Association
National may refer to:
Common uses
* Nation or country
** Nationality – a ''national'' is a person who is subject to a nation, regardless of whether the person has full rights as a citizen
Places in the United States
* National, Maryland, c ...
(NMMA) of the USA maintains its own TC-W line of standards.
References
External links
* {{HowStuffWorks, page=two-stroke, name=How Two-stroke Engines Work, author=
Brain, Marshall
Two-stroke
Engine lubrication systems