Caution!. The choice and risk are yours, as with any oil you choose. I'm just passing on a nugget of knowledge for those who want to delve a little more into the theory of lubrication and the selection criteria for each situation.
First of all, let me say that the following is the result of many months
of research on the theory of lubricants, tribology and on the specialized
websites for the subject, so don't start me with the familiar moto: "I've
been using this oil for years and I have no problem...". Here, I try to
convey the "juice" of all this research, as simply as possible, so
that you understand what you should be looking for. If you don't like my conclusions,
you are free to choose whatever oil you want (after all you are the one who is
paying for it), just as you are free to create and publish your own oil guide.
Thanks, and let's get to the point:
The short answer to the topic question is - for the Greek market
- the following compromise:
1) Amsoil Premium Protection 10W-40 Synthetic (Zinc=1378 ppm,
Phosphorus=1265 ppm, HTHS=4.3 cP) The only problem with this oil is that it is
not in Toyota's recommended viscosity, which recommends 15W-40 or 20W- 50 for
Greek conditions (see comments after the suggested list)
2) Valvoline VR1 Racing 5W-50 Synthetic (Zinc=1500 ppm,
Phosphorus=1300 ppm HTHS > 4.0 cP). Here, the 5W base oil is far from 50 and
we will see that the W number must be close to the next number, because
otherwise we have a lot of Viscosity Index Improvers (VII) that break down at
high temperature and pressure conditions. Also, it is specially designed for
racing, it is not recommended for extended periods of time - although, many
users say they have no problem with daily and long-term use.
3) MAG 1 HEAVY DUTY DIESEL 15W-40 Synthetic (Zinc=1270 ppm,
Phosphorus=1150 ppm, HTHS=4.3 cP). This oil is a bit unknown and has the
problems of being a synthetic blend oil and that it is recommended for
Diesel engines. On various specialist oil user websites such as Bob
is the oil guy or Corvette
Forum there is a dichotomy as to whether we can use oils recommended for
diesel engines in gasoline engines. However, the side that supports them has
been using them for several years without problems. Otherwise, this oil has most
of the elements that our 2ZZ engine needs: the right amount of ZDDP to protect
and not damage the catalyst, the right HTHS, it has Toyota's recommended
viscosity (15W-40) for Greek conditions and it is also very cheap compared to
the other two.
I Repeat:
Caution!. The choice and risk are yours, as with any oil you choose. I'm
just passing on a nugget of knowledge for those who want to delve a little more
into the theory of lubrication and the selection criteria for each situation.
These oils contain the correct amount of ZDDP for our engine and have
the required viscosity (HTHS > 3.8 cP). The first two have a phosphorous
content in ZDDP which could, in the long term, damage your catalytic converter.
Also, there's Amsoil Z-Rod Series Synthetic (10W-30, 20W-50, all very
expensive!), Amsoil Premium Protection 20W-50 Synthetic, Valvoline VR1 Racing
Synthetic 10W-30, and Valvoline VR1 Racing 20W-50 which have Toyota’s recommended
viscosities, but are not available in the Greek Market, just like many other
oils, from other brands, are also not available in the Greek Market. Such oils
can be found on the next page from the Corvette
Forum.
The specifics of Toyota's 2ZZ-GE engine
The 2ZZ-GE is a high speed motor (8200 rpm) with Flat Tappets (the red
ones in the drawing) for the high speed LIFT mechanism. Up to about 6200 rpm
the low-mid cams are used which touch on needle roller bearings, but then the
Flat Rocker Arm Pad locks and the high-speed cams are used which are pressing
on flat tappets to push the valves down. Therefore, an oil with higher
viscosity and higher ZDDP content is required for engine longevity.
First, let me tell you how I started researching the oil subject. I
noticed that in the Celica 7th service manual and the owner’s manual
for the American market, the recommended oil was the 5W-30. But, in the Greek
owners manual for the 2ZZ-GE engine, the 5W-30 is recommended only up to about
12°C and the next recommended oils are the 10W-30, the 15W-40 and the 20W-50.
Initially, I thought this was a typographic mistake. But then I started
researching the lubrication theory and discovered that there are 2 important
parameters for our engine lubrication, the ZDDP content and the HTHS viscosity
of the engine oil. You can read about the viscosity later in the Basic Engine
Oil Theory. The basic thing you need to know is that the higher the number you
see the thicker the oil is. The low temperature viscosity of the oil is a
measurement that simulates starting a car on a cold winter day. That value has
the letter “W” after the number and has a dash after the W. The high
temperature viscosity is the number after the dash and is related to the
viscosity of the oil as it is moving around your engine after the car has
warmed up and is at normal engine temperature of 100°C. In the 5W-30 example,
the 30 defines the viscosity of the oil at normal engine temperatures. The High
Temperature High Shear (HTHS) viscosity is measured at 150°C. It simulates the
narrow tolerances and high speeds between moving parts within a hot engine, in
particular bearings, camshaft, piston rings and cylinder liners. Shear stress:
The force needed to overcome one sliding layer of fluid to another.
Below follows the basic theory in summary:
Automotive oil – How it is blended from base oil
Base oil provides the start point. Valvoline’s automotive oil, for
example, uses high quality Group III base oil. Other methods include Gas to
Liquid (GTL) or Group IV Polyalphaolefin (PAO) base oil.
With a 5W-30 multigrade oil, the “30” relates to a viscosity of 9.3 to
<12.5 cSt at 100°C. To achieve this viscosity, a 4, 6 or 8 cSt base oil is
used.
Viscosity Modifiers (VM), known also as Viscosity Index Improvers (VII),
are added to “thicken” the oil’s viscosity when it is at 100°C. By using a low viscosity
base oil, with thickeners, the cold start and normal operation temperature
viscosity standards can be achieved. Oil chemists develop a balanced set of
additives that play specific roles but do not counteract each other.
Film strength
The ability of an oil film to withstand pressure due to load,
temperature and speed. A loss of film strength promotes metal to metal contact,
creating wear. A shear-stable oil retains its film strength. An oil can lose
its shear stability by the depletion of the Viscosity Modifier (VM or VII).
“Effects of Shearing
How does an oil lose some of it’s viscosity in an engine?
Shear stability is a measure of the amount of viscosity an oil may lose during
operation. Oil experiences very high stresses in certain areas of the engine
such as in the oil pump, cam shaft area, piston rings, and any other areas
where two mating surface areas squeeze the oil film out momentarily . Most
multigrade engine oils contain special types of additives, called Viscosity
Index improvers, which are composed of very large, viscosity-controlling
molecules. As the oil passes through the engine, these molecules are
permanently sheared or torn apart over time, causing the additive to lose its
viscosity-contributing advantages which reduces the oils ability to maintain
its higher number. ie.. 10w30,
Synthetic oils do not rely as much on special Viscosity Index Improver
additives and will experience little permanent viscosity loss.”…
“Wear Protection
Keeping the parts of an engine moving past each other is a big part of
what an engine oil does. The viscosity or thickness of the oil film on these
parts play a role in making this happen – but so does other additives that have
proven effective when added to the engine oil. Oil makers use these to make the
engine more robust and make claims about their advanced their durability. Every
surface no matter how smoothly polished at the microscopic level is made up of
mountain peaks and valleys (these are called asperities). What these additives
do is create a “snow cap” layer on the peaks that gets brushed off and
replenished as the two surfaces rub past each other. This layer prevents the
metal from wearing away and can greatly improve the life of engine components.
Engine oil, fortified with these additives, flows constantly through the engine
thereby maintaining this layer over the duration of the oil drain interval.
When all these additives are used up, it is time to change the oil.”…
“What does this shearing do to your oil and engine in the long term?
When the oil film is sheared or squeezed out, then your protection is now
reliant on barrier lubricant additives. Oil has 3 states of lubrication,
hydrodynamic, mixed film, and boundary(barrier). The best is hydrodynamic which
is nothing more than a flow of oil separating two mating surfaces. After a
period of time shearing, the oil will lose it’s ability to hold up to the same
flow as before since the VI Improvers are breaking down causing the oil to thin
down in grade. Once this happens, there is less film strength between the
mating surfaces so it doesn’t take as much for the oil to shear, therefore
creating more heat which attacks the base oil even more and then starts to
cause the oil to thicken up due to the excessive levels of heat and the broken
down VI Improvers become a contaminant which added to the existing oil will
continue to thicken and ultimately cause sludge if not changed in a reasonable
time..”…
“Conclusion
Base stock oils (especially the newer GF-3 SL) have better resistance to
heat like a synthetic does.
The higher the spread between the bottom number and
the top number (eg. For 0W-40 the spread is 40-0=40) the more VI improvers are
relied on for maintaining the viscosity. Better to keep the numbers closer.
(eg. 15W-40 is better than a 0W-40 oil)
All base oils film strength will shear under stress or
pressure. The real way to help prevent wear is to maintain higher levels of
antiwear additives This in conjunction with a good base stock which resists
breakdown to high heat.”…
Therefore, as per Toyota recommendations the best oil viscosity for
Greek temperatures would be a 15W-40, or even a 20W-50 that have a good base
oil and a high HTHS. Now, let’s look at ZDDP:
Zinc dialkyl dithiophosphates (ZDDP)
An anti-wear additive found in automotive engine oil called Zinc dialkyldithiophosphates (ZDDP).
This is an extract of an article by Richard Long of the
Southern Classics Society, first published in
the TVR Magazine:
“Classic car petrol engines (1950 through to 1990) will by now have many
years and miles under their pistons, and their care is just as important as
modern day units; perhaps even more so. What may be good oil for one type of
engine could be an anathema for another. So what do classic car engines need
from oil that is suitable for their longevity and protection?
One of the key components is the zinc level in oil and this is defined
as "parts per million (ppm)".
The zinc element is actually contained within a compound called
Zinkdialkyldithiophosphate (ZDDP] and its inclusion is a critical factor for
old style engines. Through past decades the level of ZDDP has been decreasing
due to modern catalytic convertors and far more efficient engine design. Modern
"cats” cannot deal or survive with the phosphorus that is also contained
within ZDDP; as a result modern car manufacturers have progressively required a
reduction of this additive in oil. That’s understandable. However, where does
that leave a classic car owner in deciding what oil to choose for their classic
car in the 21st Century?...
…So as you can see the force placed upon the bottom of the cam follower
is significant to say the least. This "super-pressure" contact causes
friction and as we know friction causes component wear. This is where ZDDP
plays its part. Zinc is a polar molecule, so it is attracted to steel surfaces.
Under high heat and extreme load (pressure), the Zinc reacts with the
steel surface and creates a phosphate glass film that protects the steel
surface by forming a sacrificial layer that covers the peaks and fills in any
indents on the steel surface. Basically your flat bottomed follower really does
become 99.9% flat and smooth. By forming this protective layer the cam lobes
and flat bottomed followers are heavily protected against friction wear;
remember friction wear can never be eliminated but much can be done to slow the
process down.
So ideally to get the best protection the oil needs a high ZDDP, but
modern oils of today do not contain this but rather "other additives“
which oil manufactures keep close to their chest as it’s all about marketing
and protecting their "recipe”. That is little or no comfort for the
classic car owner who relies on a decent multigrade mineral oil with a generous
level of ZDDP contained therein.
Of significance, many oils that say "classic car oil" do not
actually contain enough ZDDP or worse still a mere trace. So, what level of
this additive does a classic car owner require to feel confident that the oil
in their car engine Is not only lubricating but also protecting those parts
under extreme pressure. Without a doubt an owner should be looking for an oil
that contains a minimum of 1000ppm of ZDDP and to a maximum of 1600ppm. In fact
an oil containing in excess of 1500ppm may cause more harm than good; such high
levels of ZDDP are specifically manufactured for race engines and It is not an
oil that can be purchased off the shelf…
…[From the introduction of API SJ in 1996 the API Classifications were
more focused on the control of engine oil components that contributed to
catalyst poisoning. And wouldn’t you
know it, one of the main contributors to catalyst poisoning was phosphorus from
ZDDP! So, from API SJ on, there has been a move away from zinc based anti-wear
agents, including limiting the phosphorus content of a Passenger Car Motor Oil
(PCMO) to below 1000ppm. The zinc level of an engine oil was no longer an
absolute indication of that engine oil’s anti-wear performance.
API SH Zinc: 1300 ppm max, Phosphorus: 1200 ppm max
API SL/SJ Zinc: 1100 ppm max, Phosphorus: 1000 ppm max
API SM Zinc: 870 ppm max, Phosphorus: 800 ppm max]
So, we need an oil with a specification of API SL/SJ and older!
Difficult to find but there are some oils that specifically have high levels of
ZDDP.
Do Older Engines Need Oil With ZDDP Additives? (From Amsoil blog)
…because the zinc and phosphorus found in ZDDP can negatively affect catalytic
converters, it has been phased out of motor oil formulations in recent years.
Reducing ZDDP has drawbacks, as classic-car owners have found. Older
vehicles with flat-tappet camshafts and, in particular, engines that include
high-tension valve springs or other modifications that create high contact
pressures, can suffer premature wear due to reduced ZDDP levels.
For best protection, engine builders and gearheads typically use
high-zinc and high-phosphorus motor oil to offer extra protection for
flat-tappet cams, lifters and other components during break-in.
AMSOIL Break-In Oil, for example, contains 2,200 ppm zinc and 2,000 ppm
phosphorus.
How do ZDDP additives work?
ZDDP anti-wear additives are heat-activated, meaning they provide wear
protection in areas of increased friction.
As temperatures rise and surfaces come closer together, ZDDP decomposes
and the resulting chemistry protects critical metal surfaces.
When parts move during operation, any sliding or rolling motion takes
place on top of or within the ZDDP anti-wear film, which reduces metal-to-metal
contact.”
…The role of piston rings
Even though Hugh didn’t ask about it specifically, I should also mention
the importance of seating the piston rings during break-in.
Although a new or freshly honed cylinder appears smooth to the naked
eye, it actually contains microscopic peaks and valleys. If the valleys are too
deep, they collect excess oil, which burns during combustion and leads to oil
consumption.
The sharp peaks, meanwhile, provide insufficient area to allow the rings
to seat tightly. That means highly pressurized combustion gases can blow past
the rings and into the crankcase, reducing horsepower and contaminating the
oil.
Find out why championship engine builder Jesse
Prather requires his customers to use AMSOIL Break-In Oil.
Breaking in the engine wears the cylinder-wall asperities, providing
increased surface area for the rings to seat tightly. The result is maximum
compression (i.e. power) and minimum oil consumption.
Do you always need an oil with ZDDP additives?
Do you need to use high-zinc motor oil in an older engine after break-in, which is typically about 500 miles?
Yes, if you want to maintain horsepower and promote longevity.
Even after the cam has seasoned, it’s still exposed to tremendous heat and pressure, especially in a heavily modified or racing engine. The constant barrage of pressure can rupture the oil film responsible for preventing wear, leading to metal-to-metal contact.
After break-in, we recommend using an oil with at least 1,000 ppm ZDDP in a flat-tappet engine.
That way, you’re providing your expensive engine with
maximum protection against wear and horsepower loss.”
If you have the patience you can read the theory behind all these, in the following post:
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