SYNTHETIC VS MINERAL OIL Introduction Oil is the life blood of an engine and just like the b lood in our bodies, it is required to fulfill a number of functions. Oil does not only lubricate, it also carries a way heat, dissolves contaminants, carries away debris and provides a working medium for such things as hydraulic lifters. All oils, whether mineral or synthetic, have additives mixed into the package which fortifies the oil to do its job. The majority of finished lubricants thus all consist of a base oil or a mixture of different base oils! and a additive package. "hen we refer to the oil being either either mineral or synthetic, we we thus refer to its base oil component. The The American #etroleum #etroleum $nstitute A#$! A#$! produces a chart that classifies classifies the different different base oil types types . %ee &ig '. '. (roup
%aturate wt )
%ulphur wt )
*iscosity $ndex
$
+ - andor
/ -.-0
/ 1- to + '2-
$$
3 - and
4 -.-0
3 1- to 4 '2-
$$$
3 -
4 -.-0
3 '2-
$*
All poly alpha olefins #AOs!
*
All base stocks not included in (roups $5$*
Fig 1. API – Clai!ication o! "a# oil
S$nt%#tic S$nt%#tic & Min#ral The differences between these types of oils are all in the molecular make5up. (roups $ and $$ are typically classified as mineral base oils, are crude derived and consist mainly of hydrogen and carbon hydrocarbon! molecules. (roup $$ and $$$ type base stocks help to formulate more economic type semi5synthetic lubricants. These first three base oil groups are widely used in combination combination with additive packages, ester oils oils (roup *! andor (roup $* polyalphaolefins in order to formulate semi5synthetic based lubricants. (roup $$$ base oils are sometimes considered considered as synthetic synthetic when it is hydro5isom hydro5isomeri6 eri6ed. ed. *arious *arious petrochemical petrochemical companies companies have developed developed processes involving catalytic conversion of feed stocks under pressure in the presence of hydrogen, into high quality mineral lubricating oil. This process was called hydro5cracking or hydro5isomeri6ation. hydro5isomeri6ation. $n 2--7 production of gas5to5liquid (T8! of (roup $$$ base stocks began. 9ven though they are considered a synthetic product, they are still mineral base stocks and counted as the mineral part of all semi5synthetic lubricants. lubricants. %emi5synthetic %emi5synthetic oils are blends of mineral oil with no more than 0-) synthetic oil. These oils are designed to have many of the benefits of synthetic oil without matching the cost of pure synthetic oil, :ineral oil being a product of nature has lots o f different si6ed molecules in its makeup. %ynthetic oil on the other hand, hand, has a very very consis consisten tentt molecu molecule le si6e si6e which which gives gives the synthe syntheti tic c materi material al a contr controll olled ed struct structure ure with with predictable properties. %ynthetic base stocks are man5made and sophisticated, unlike mineral base oils which are complex mixtures of naturally occurring hydrocarbons.
T%# %itor$ o! $nt%#tic oil %ynthetic oils are not new. new. As a matter of fact, the first first real synthetic engine oils were used in aircraft engines engines in "orld "ar $$ concurrently by (ermany and the ;nited %tates. 9asing engine starts in winter and avoiding soot deposits were the two main drivers for the ;% Air &orce, while the motivation in (ermany perhaps was primarily related to resource issues. The first synthetic oils for aircraft engines were based on blends of an acid ester and polyethylene oil. $n the early '<-s, =hevro =hevron n ;%A integrate integrated d the first first commercia commerciall utili6at utili6ation ion of hydro5c hydro5cracki racking ng technolog technology. y. >y '0 the company introduced iso5dewaxing technology making them one of the world?s largest manufacturers of A#$ (roup $$ and $$$ base oils. On ' @uly 2---, =hevron =orp. combined efforts with #hillips #etroleum =o. now =onoco# =onoco#hill hillips, ips, to become become =hevron =hevron #hillips #hillips =hemical =hemical =ompany, =ompany, one of the top producers producers of poly5alph poly5alpha a olefin #AO! (roup $* base stocks.
The first synthetic oil developed for automotive combustion engines and fully recogni6ed by the American #etroleum $nstitute A#$! was produced in '2. This first A#$5rated synthetic motor oil meeting A#$ %9== specifications was based on a %A9 '-"5B- grade Ci5ester A#$ (roup * formulation. T%# Pro and Con o! S$nt%#tic The advantage of synthetic oils is that it potentially has a more stable suite of properties that can be tailored to a wider range of applications. This is why one can now find oils that can cover huge viscosity ranges such as '7"<- and even O"0-. There are definite advantages to this ability but careful consideration of application is necessary. Advantages of synthetic motor oilsD >etter low and high temperature viscosity performance Cecreased evaporative loss Eesistance to oxidation, thermal breakdown and sludge deposits >etter chemical F shear stability >etter lubrication on cold starts 8onger engine life #ossible extended drain intervals with the environmental benefit of less oil waste $mproved fuel economy in certain engine configurations • • • • • • • •
Cisadvantages of synthetic motor oils include 8ower friction characteristics may make them unsuitable for running5in applications #otential compatibility problems when mixed with mineral oils. :any modern cars now come with synthetic oil as a factory fill #otential decomposition problems in certain chemical environments #otential stress cracking of plastic components like poly5oxy5methylene in the presence of #AO %ynthetics do not hold lead in suspension as well as mineral oil, caution is thus advised when runing on leaded fuel • •
• • •
Concluion There is a popular belief that if high priced synthetic oil is used in an engine, oil changes can be extended exponentially and that there will be a huge increase in efficiency. Go matter what the main constituent of the oil is mineral or synthetic! a large proportion of the content are additives, research has shown that the lifetime of the additives the time it takes to lose its useful properties! is primarily dependent on the service duty of the engine. $t is in fact the depletion of these additives that dictates when an oil should be changed. Got all oils are created equal but all of them do wear out at approximately the same rate as the additives are depleted. The bottom line is that frequent oil changes are better for an engine.
