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THE DIRTY TRUTH ABOUT SOOT

What is soot?

Soot is principally made up o carbon and occurs as a result

o the incomplete burning o uel, whether it is by a ickering

candle or a diesel engine. When clean uel burns completely

the only by-products are water and carbon dioxide. However,

due to impurities in the uel, inefciencies in the combustion

cycle o an engine and high engine temperatures, soot

and other by-products, such as nitrogen oxides (NOx) are

produced. These emissions are treated by systems such

as Exhaust Gas Recirculation (EGR) or Selective Catalytic

Reduction (SCR) systems with Diesel Particulate Filters (DPF).

While most soot and other by-products exit through the engines

exhaust system, a percentage is absorbed by the engines lubricant.

In EGR systems a portion of the engine exhaust is re-introducedinto the combustion chamber to control the gaseous emissions,

which add to higher levels of soot loading in the lubricant.

Although soot particles in engine oil are sub-micron-sized,

they tend to agglomerate to orm larger particles (See Figure 1).

While all modern diesel-engine lubricants have additives known

as dispersants to help reduce this clumping, the build up o soot

over time eventually results in a thickening o the oil. This occurs

because clumps o soot trap oil within them causing the oil to

behave as though it is made o larger, more viscous molecules.

I soot is not well dispersed in the lubricant, sludge will orm

on the flter, rocker covers and cylinder head deck. Filterblockage can occur i the flter element becomes covered in

sludge, which will cause high dierential pressure across the

flter and cause it to go into bypass mode, allowing unfltered

oil to circulate through the engine. Sludge accumulation on the

cylinder head deck can potentially lead to an increase in valve

guide wear.

What does this mean or your engine?

The principal problem or engines is that agglomerated soot

is abrasive. While sub-micron-sized particles can ow reely

through an engines components, the presence o agglomerated

soot between two sliding suraces, a piston ring and liner or

bearing and journal or example, can act like sandpaper and

cause abrasive wear. As soot levels increase throughout the oil

drain interval, the ability o the oil to minimize agglomeration

becomes a critical deence against wear.

I soot is allowed to agglomerate, it can gradually wear down

engine components and signifcantly aect the efciency and

power output o the engine. Pistons that are scored as a result

o the presence o soot particles can leak uel and air during

the compression cycle, reducing the engines horsepower.Similarly, valve train component wear can result in a loss o uel

economy, as injection and valve timing can change, resulting in

a retardation o the uel injection timing, causing more soot to

be generated.

Another outcome o agglomerated soot in the oil is higher

viscosity levels. Higher viscosity oil will have lower pumpability

and possibly leave the engine under-lubricated. This is

particularly dangerous during cold weather start-ups when oil

ow is reduced by low ambient temperature and the engine

is the most vulnerable to oil-pumping ailure. Soot loading

also aects the High Temperature High Shear (HTHS)properties o a lubricant, which will result in a loss o uel

economy over the drain interval.

A fnal, less common, but equally damaging eect o soot

accumulation in engine oil is stuck rings caused by soot

deposits. Using the wrong engine oil can result in the groove

that the ring runs in getting gummed up with sludge and

What is the HT dierence? Petro-Canada starts with the patented HT purity process to produce crystal-clear,

99.9% pure base oils. The result is a range o lubricants, specialty fuids and greases that deliver maximum

perormance or our customers.

TechBulletinPetro-Canada

One by-product has remained a constant since Daimler developed the frst prototype o

todays modern diesel engine in 1886 soot. Even in todays most advanced engines which run

on ultra low sulphur uel, soot can have a signifcant impact on the perormance and longevity

o an engine. In act, as engine loads get heavier and drain intervals are extended urther

and urther, the relevance o soot has never been greater. However, there are steps that can

be taken to minimize the eects o engine soot or improved operations and costs savings.

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carbon, preventing the ree movement o the ring within the

cylinder. This can lead to a condition called blowby, where

unburned uel and gases pass by the rings and blow into

the crankcase, robbing the engine o power, decreasing uel

economy, increasing oil consumption and the chance o

serious engine ailure.

What can you do?

To help fght the negative eects o soot and prolong thelie o your engine, it is important to select an engine oil with

excellent soot handling properties. There are two principal

points to consider when selecting a heavy duty engine oil:

That it is ormulated with base oils produced through

advanced refning processes. Based on a comparison

o Mack T-11 test results, engine oils ormulated with

Petro-Canadas 99.9% pure base oils and proprietary

additive system signifcantly outperorm competitive

group II base oil/additive combinations in both soot

dispersion and ability to reduce agglomeration.

That the heavy duty engine oil has eective dispersantadditives to handle the soot and prevent it rom clumping

and changing the oils viscosity. Petro-Canadas DURON-E

is blended with specialty additives or longer-lasting

protection against the damage soot causes. As a result,

DURON-E is better able to micro-disperse soot particles

and prevent clumping to better protect engines rom

abrasive wear.

Recent research has shown that dispersant perormance is

enhanced by the purity o the base oil used. Ultra pure base oils

can improve soot dispersion efciency, allowing the engine oil to

disperse more soot or the same amount o dispersant additive.

By choosing a higher quality engine oil that handles soot

better, both eet and heavy duty equipment operators

should be able to extend drain intervals with the use o an oil

analysis program. Fuel economy plays a part in extending the

oil drain interval as well. For instance, a truck with better uel

economy would typically be less demanding on the lubricant

than one with poorer uel economy, given the same oil

consumption rate. Fuel rate is an indication o the heat input

into an engine, which can aect the rate o oxidation o

the lubricant and deposit ormation. Thereore, it appears

that poorer uel economy would also equate to a higher

soot loading o the lubricant. Making an inormed engine oil

selection will help operators improve engine perormance

and protect their engines longer or greater reliability and

reduced downtime.

Figure 1: MACK T-11 Drain Samples

Good

(DURON-E Synthetic 10W-40)6% soot, 228 hrs

Bad

(Group II Base Oil & CJ-4 Chemistry6% soot, 204 hrs

TechBulletin Ino LinesI you would like inormation about the many Petro-Canada lubricants, specialty uids and greases, please contact us at:

Petro-Canada is a Suncor Energy businessTM Trademark of Suncor Energy Inc. Used under licence.

Petro-Canada Lubricants Inc.

2310 Lakeshore Road West

Mississauga, Ontario

Canada L5J 1K2

Canada West .................... Phone 1-800-661-1199

Canada East (English) ....... Phone 1-800-268-5850

Canada East (French) ........ Phone 1-800-576-1686

Other Areas ....................... Phone 1-416-730-2408E-mail ................................ lubecsr@suncor.com

Internet ............................. lubricants.petro-canada.ca

Petro-Canada Europe Lubricants

Wellington House, Starley Way

Birmingham International Park

Solihull B37 7HB United Kingdom

Phone ............................... +44 (0) 121 781 7264

Fax ................................... +44 (0) 121 781 7401

Petro-Canada America Lubricants

980 North Michigan Avenue

Suite 1400, #1431

Chicago, Illinois USA 60611

Phone ............................... 1-888-284-4572

Petro-Canada Asia Pacifc Holding Company Ltd.

Jia Shi Lubricants Trading (Shanghai) Co. Ltd.

1908 World Trade Tower

500 Guangdong Road, Huangpu District

Shanghai, China 200001

Phone ............................... +86-21-6362-0066

TB1203E (2011.10)

Few large aggregates

Well dispersed sample

Largest aggregate sizes ~300-400 nm

More large aggregates

Poorly dispersed sample

Largest aggregate sizes ~700-800 nm

Learn more at www.fghtsoot.com

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