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Technical Service Bulletin

OBJECTIVE:

To provide information about the use of motor oils formulated

with lower levels of zinc and phosphorus additives in

ISSUES:

Engine oils contain anti-wear additives. The most common

anti-wear chemistry is zinc dithiophosphate (ZDP), which is

a combination of zinc and phosphorus. In 2005 the American

Petroleum Institute (API) and International Lubricants

Standards Approval Committee (ILSAC) instituted API SM

and ILSAC GF-4 quality standards. These two standards

are closely related, with GF-4 being viscosity dependent and

API SM applying to all SAE automotive viscosities.

API SM/ILSAC GF-4 licensed oils with viscosity grades

0W-20 & 30, 5W-20 & 30, and 10W-30 are restricted

to .06 - .08% phosphorus, while previous API SL/ILSAC

GF-3 oils were restricted to .1% phosphorus. There is concern

that oils containing lower levels of phosphorus are insufficient

in protecting the high-contact regions of the flat

tappets and camshaft lobes found in many older cars and

high-performance engines.

TECHNICAL DISCUSSION:

During the development of API SM/ILSAC GF-4 the antiwear

requirements of flat tappets were given particular consideration

by the engine manufacturers and by the oil industry.

Engines with flat tappets were used to qualify API SM/

ILSAC GF-4 oils. The anti-wear requirements of these tests

are severe. In one case where the same Sequence IVA engine

test was used for previous higher zinc and phosphorus

oils, the average camshaft wear limits were reduced, allowing

RECOMMENDATION:

For all new or rebuilt engines with flat tappets, proper assembly

lubes and oil additives should be used during the

break-in phase. These additives provide extra protection at

the point of contact, helping the flat tappet face to properly

mate with the cam lobe. Once the break-in phase is over,

these additives should not be used. This includes the GM

product E.O.S., which is an assembly lubricant only and is

not to be used, as the label clearly states, as an engine oil

additive.

High-performance modified engines benefit from oils with

superior film strength and anti-wear properties. The flat

tappet/camshaft lobe interface is the one area in an engine

that has extreme contact load. That load increases significantly

where non-stock, high-pressure valve springs are

used. The use of properly formulated engine oils for this

application will help reduce wear and extend the flat tappet/

camshaft life.

There are many more ways to achieve good anti-wear performance

than just using zinc and phosphorus compounds

alone. Zinc and phosphorus are widely used because they

are the most cost effective solutions to achieve anti-wear

properties.

AMSOIL INC., AMSOIL Bldg., Superior, WI 54880 (715) 392-7101 © Copyright 2006

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Technical Service Bulletin

In addition to zinc and phosphorus compounds, AMSOIL

combines "ashless" anti-wear and friction modifier additives

with high quality synthetic oils to achieve truly superior

anti-wear performance, including in flat tappet applications.

AMSOIL 0W-30 (TSO), 5W-30 (ASL) and 10W-30

(ATM) are premium synthetic, API SM (gasoline)/CF

(off-road diesel)/ ILSAC GF-4 formulations containing a

proprietary combination of zinc and phosphorus, detergent

and friction modifier additives to generate exceptional

anti-wear properties as demonstrated in the four-ball wear

test. These oils are recommended for use in newer and

older engines with flat tappets in both stock and highperformance

configurations.

AMSOIL 20W-50 (TRO) is a premium synthetic racing

oil for gasoline engines with superior film strength and

anti-wear protection. It is excellent for street or race use in

cars, hot rods, and trucks or boats. It is the preferred

choice for highly modified, high horsepower engines.

AMSOIL 10W-40 (AMO), 15W-40 (AME) and 20W-50

(ARO) are premium synthetic, API SL (gasoline)/CI-4

Plus (heavy-duty, on-road diesel) quality formulations.

They are an excellent choice for those who desire diesel

style engine oils recommended for use in both gasoline

and diesel engines.

AMSOIL INC., AMSOIL Bldg., Superior, WI 54880 (715) 392-7101 © Copyright 2006

Page 1 of 2

Technical Service Bulletin

OBJECTIVE:

To explain how certain AMSOIL engine oils can

qualify for both monograde and multigrade viscosity

ratings.

TECHNICAL DISCUSSION:

In selecting a proper engine oil, the vehicle owner

must consider both the oil viscosity and the lubricant

service requirements for the vehicle. To enable the

owner to identify a proper oil, the vehicle manufacturers

and the lubricant industry have developed a lubricant

classification system (1).

When automobiles first appeared, attempts were made

to identify motor oils. Viscosity was known to be one

of the most important characteristics of an oil, and it

was simply classified as light, medium or heavy, depending

on its viscosity.

When more advanced instruments were made available

to measure viscosity, the Society of Automotive

Engineers (SAE) developed a better oil classification

system. This system, known as SAE J300 (1), was

Another way to classify the oil is to add the letter “W”

behind the number. The “W” stands for winter and

indicates that an oil is suitable for use in colder temperatures.

The lower the number in front of the “W,”

the better the cold temperature protection. This service

classification mainly looks at the low temperature

viscosity of the oil. For example, the following table

lists the requirements of the low temperature cranking

viscosity at different temperatures:

AMSOIL INC., AMSOIL Bldg., Superior, WI 54880 (715) 392-7101 © Copyright 2006

20

Less than

5.6 9.3

30

Less than

9.3 12.5

40

Less than

12.5 16.3

50

Less than

16.3 21.9

60

Less than

21.9 26.1

0W 6200 at –35

5W 6600 at –30

10W 7000 at –25

15W 7000 at –20

20W 9500 at –15

25W 13,000 at –10

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Technical Service Bulletin

AMSOIL INC., AMSOIL Bldg., Superior, WI 54880 (715) 392-7101 © Copyright 2006

SAE 20 and SAE 20W are two totally separate monograde

classifications. SAE 20 describes the high temperature

viscosity of the oil and SAE 20W describes

the low temperature cranking capability of the oil.

In order to allow engines to start at low temperatures

while providing sufficient viscosity at high temperatures

to protect engines against wear, multigrade oils

were developed. An oil can be classified as a multigrade

SAE 20W-20 if the oil can meet both the low

RECOMMENDATIONS

AMSOIL ACD and ASE 10W-30/SAE 30 engine oils

can be used in any applications requiring a monograde

SAE 30 or multigrade SAE 10W-30 engine oil with

the performance specifications listed for each product.

AMSOIL ACD has a performance emphasis on heavy

duty on-road diesels with an API CI-4 Plus rating,

while it is also applicable for gasoline engines with its

API SL rating.

AMSOIL ASE has a performance emphasis on small

gasoline and diesel engines used for commercial service

or by the homeowner. AMSOIL ASE carries the

API SL rating for gasoline and API CF/CD rating for

off-road diesels.

REFERENCES

1. Society of Automotive Engineers, Publication J-

300, December 1999.