oilman

iTrader: (9)

Ok, I'm fed up with all the rubbish that is posted when anyone asks a question on oil so, here is some proper advice written by an expert.

This advice is copied but the Author is well known to me and I have his permission to post it.

If you wish to understand what it's all about then you'll not find a better written article about "Lubricating the Subaru"

Lubricating the Subaru.

Basically

Basically, to use that irritating in-word, engine lubrication is simple, and consequently boring. So I intend to treat the subject “complicatedly”, which may not be an in-word, but makes life far more interesting!

So, to take a quick look at the simple picture; the oil keeps moving parts apart, reducing friction and carrying away heat. Where there is metal-to-metal contact there are chemicals in the oil to reduce damage. Because the internal combustion process is always less than perfect, some soot is produced and this must be washed off the pistons and rings by the oil, so it has a cleaning or detergent function as well.

The trouble is, all this is just as true for Henry Ford’s original Model T engine as it is for the Subaru or any other high output motor. So where is the difference?

The Model T, with 10bhp/litre at 2,000rpm and a single underhead camshaft, was filled with a thick, greenish liquid from somewhere near the bottom of the distillation colums on the Pennsylvania oilfields. It did a vague tour of the internals by guesswork (there was no oil pump) at a temperature around 50 degC, and lasted for 1,000 miles. On the plus side, some of the impurities acted as anti-wear and detergent chemicals. They didn’t work very well, but it was better than nothing. The engine wore out in around 20,000 miles, but even ordinary people, not just amateur rally drivers, were happy to put up with this.

The difference begins with the first turn of the key. The modern high-pressure pump would cavitate on the old heavy monogrades, starving the bearings for a vital couple of seconds, even in warm weather. Likewise, cam lobes would suffer as the sluggish oil found its way along narrow oil ways to the valve gear. The turbo bearing already spinning fast, would also starve, and when it got going, how long would it be before the heat soak-back fried the primitive oil into a lump of carbon? (This was the problem with “modern” oils only 15 years ago).

So, a good oil must be quite low in viscosity even in the cold, so that it gets around the engine in a fraction of a second on start-up. On the other hand, it must protect engine components (piston rings for example) at temperatures up to 300 degC without evaporating or carbonising, and maintain oil pressure.

Unmodified thin oils simply can’t manage this balancing act. The answer is to use a mixture of thin oil and temperature-sensitive polymer, so as the thin oil gets even thinner with increasing temperatures as the engine warms up, the polymer expands and fights back, keeping the viscosity at a reasonable level to hold oil pressure and film thickness on the bearings. This is called a multigrade.

But, this is all too basic! What I have just written was and is relevant to a 1958 Morris Minor.

The questions that Subaru owners need to ask are: “Will this thin oil evaporate and be drawn into the intake manifold (via the closed circuit crankcase ventilation), leading to combustion chamber deposits and de-activated catalysts?” and “Will the polymer shear down at high engine revolutions and high temperatures, causing low oil pressure and component wear?” and “Will it carbonise on the turbo bearing?” These are 21st century questions which cannot be answered by a basic 1990’s approach.

BUT! Before we head into more complications, some figures………

The SAE Business (American Society of Automotive Engineers)

Viscosity is the force required to shear the oil at a certain speed and temperature. Oils work because they have viscosity; the drag of a rotating part pulls oil from a low-pressure area into a high pressure area and “floats” the surfaces apart. This is called “hydrodynamic lubrication”, and crank bearings depend on it.

In fact a plain bearing running properly shows literally no metal-to-metal contact. Experimental set-ups have shown that electrical current will not flow from a crank main bearing to the shells. Also, the energy loss due to friction (the co-efficient of friction) is incredibly low, around 0.001. So for every kilogram pulling one way, friction fights back with one gram. This is very much better than any “dry” situation.

For example, the much over-rated plastic PTFE has a co-efficient of friction on steel of 0.1, 100 times worse than oil.

Oil viscosities are accurately measured in units called “Centistokes” at exactly 100 degC. These fall into five high temperature SAE catagories:-

SAE No.........20..........30...............40........ .........50...............60
VisRange..5.6-<9.3..9.3-<12.5...12.5 <16.3....16.3-<21.9....21.9 - <26

A decent quality oil usually has a viscosity that falls in the middle of the spec, so a SAE 40 will be about 14 Centistoke units, but SAE ratings are quite wide, so it’s possible for one 40 oil to be noticeably thicker or thinner than another.

When the polymer modified multigrades appeared, a low temperature range of tests were brought in, called “W” for winter (it doesn’t mean weight). These simulate cold start at different non-ferrous monkey endangering temperatures from –15 degC for the 20w test to a desperate –35 degC for 0w.

For example, an SAE 5w-40 oil is one that has a viscosity of less than 6600 units at –30 degC, and a viscosity of about 14 units at 100 degC.

Now, those of you who have been paying attention will say “Just a minute! I thought you said these multigrade polymers stopped the oil thinning down, but 6600 to 14 looks like a lot of thinning to me!”. Good point, but the oil does flow enough to allow a marginal start at –30 degC, and 14cst is plenty of viscosity when the engine is running normally. (A lot more could damage the engine.

The vital point is, a monograde 40 would be just like candle wax at –30 degC, and not much better at –10 degC. It would even give the starter motor a fairly difficult time at 0 degC. (At 0 degC, a 5w-40 has a viscosity of 800 but the monograde 40 is up at 3200!)

Another basic point about wide ranging multigrades such as 5w-40 or 0w-40 is that they save fuel at cruising speeds, and release more power at full throttle. But complications arise……..

Building a good oil

A cave may not be the best place to live, but it’s ready-made and cheap. This is the estate agent’s equivalent of an old style monograde oil. Or you could get Hengist Pod to fit a window and a door; this is moving up to a cheap and cheerful mineral 20w-50. But an architect-designed “machine for living in”, built up brick by brick, is an allegory of a high performance synthetic oil.

It is impossible to make a good 5w-40, or even 10w-40, using only mineral oil. The base oil is so thin, it just evaporates away at the high temperatures found in a powerful engine that is being used seriously. Although there are chemical compounds in there to prevent oil breakdown by oxygen in the atmosphere (oxidation) they cannot adequately protect vulnerable mineral oil at the 130 degC plus sump temperatures found in hard worked turbocharged or re-mapped engines.

Synthetics are the answer. They are built up from simple chemical units, brick by brick so as to speak; to make an architect-designed oil with properties to suit the modern engine.

But sometimes, if you look behind the façade, there is a nurky old cave at the back! This is because the marketing men have been meddling!

The Synthetic Myth

What do we mean by the word “synthetic”?

Once, it meant the “brick by brick” chemical building of a designer oil, but the waters have been muddied by a court case that took place in the USA a few years ago, where the right to call heavily-modified mineral oil “synthetic”, was won.

This was the answer to the ad-man’s dream; the chance to use that sexy word “synthetic” on the can….without spending much extra on the contents! Most lower cost “synthetic” or “semi-synthetic” oils use these hydrocracked mineral oils. They do have some advantages, particularly in commercial diesel lubricants, but their value in performance engines is marginal.

TRUE synthetics are expensive (about 6 times more than top quality mineral oils). Looked at non-basically there are three broad catagories, each containing dozens of types and viscosity grades:-

PIB’s (Polyisobutanes)

These are occasionally used as thickeners in motor oils and gear oils, but their main application is to suppress smoke in 2-strokes.

The two important ones are:

Esters

All jet engines are lubricated with synthetic esters, and have been for 50 years, but these expensive fluids only started to appear in petrol engine oils about 20 years ago. Thanks to their aviation origins, the types suitable for lubricants (esters also appear in perfumes; they are different!) work well from –50 degC to 200 degC, and they have a useful extra trick.

Due to their structure, ester molecules are “polar”; they stick to metal surfaces using electrostatic forces. This means that a protective layer is there at all times, even during that crucial start-up period. This helps to protect cams, gears, piston rings and valve train components, where lubrication is “boundary” rather than “hydrodynamic”, i.e. a very thin non-pressure fed film has to hold the surface apart. Even crank bearings benefit at starts, stops or when extreme shock loads upset the “hydrodynamic” film. (Are you listening, all you rally drivers and off road fanatics?)

Synthetic Hydrocarbons or POA’s (Poly Alpha Olefins)

These are, in effect, very precisely made equivalents to the most desirable mineral oil molecules. As with esters, they work very well at low temperatures, and equally well when the heat is on, if protected by anti-oxidants.

The difference is, they are inert, and not polar. In fact, on their own they are hopeless “boundary” lubricants, with LESS load carrying ability than a mineral oil. They depend entirely on the correct chemical enhancements.

PAO’s work best in combination with esters. The esters assist load carrying, reduce friction, and cut down seal drag and wear, whilst the PAO’s act as solvents for the multigrade polymers and a large assortment of special compounds that act as dispersants, detergents, anti-wear and oxidant agents, and foam suppressants. Both are very good at resisting high-temperature evaporation, and the esters in particular will never carbonise in turbo bearings even when provoked by anti-lag systems.

Must Have MORE Power!

Motorcars are bought for all sorts of reasons, but enthusiasts like lots of power. To get more power, a lot of fuel must be burnt, and more than half of it, sadly, gets thrown away as waste heat. For every litre of fuel burnt, 60% of the energy goes as waste heat into the exhaust and cooling system.

A turbocharger can extract a few percent as useful energy and convert it into pressure on the intake side, but only 40-45% is left, and only 25% actually shows up as BHP at the flywheel. 6% goes in pumping air into the engine, 6% as oil drag losses and 2-3% as engine friction. The oil deals with 97% of the friction; so reducing the remaining few percent is not easy.

If you doubt that even ordinary oil has a massive effect, take a clean, dry 200 bhp engine, connect it to a dyno and start it up. It will only make 1 bhp for a few seconds. Now that’s real friction for you!

Oddly enough, people get starry-eyed about reducing friction, especially those half-wits who peddle silly “magic additives”, which have not the smallest effect on friction but rapidly corrode bearings and wallet contents. In fact, even a virtually impossible 50% reduction in the remaining engine friction would be no big deal, perhaps one or two bhp or a couple of extra miles per gallon.

Even More Power!

He place to look for extra power is in that 6% lost as oil drag. In a well-designed modern motor, the oil doesn’t have to cover up for wide clearances, poor oil pump capacity or flexy crankshafts, so it can be quite thin. How thin? Well take a look at these dyno results.

A while ago now, we ran three Silkolene performance oils in a Honda Blackbird motorcycle. this fearsome device is fitted with a light, compact, naturally aspirated 1100cc engine which turns out 120+ bhp at the back wheel. The normal fill for this one-year-old engine was 15w-50, so the first reading was taken using a fresh sump-fill of this grade. (The dyno was set up for EEC horsepower, i.e. Pessimistic)

15w-50
Max Power 127.9 bhp @ 9750 rpm
Torque 75.8 ft-lbs @ 7300 rpm

After a flush-out and fill up with 5w-40 the readings were;

5w-40
Max Power 131.6 bhp @ 9750 rpm
Torque 77.7 ft-lbs @ 7400 rpm

Then we tried an experimental grade, 0w-20 yes, 0w-20! This wasn’t as risky as you may think, because this grade had already done a season’s racing with the Kawasaki World Superbike Team, giving them some useful extra power with no reliability problems. (But it must be said, they were only interested in 200 frantic miles before the engines went back to Japan)

0w-20
Max Power 134.4 bhp @ 9750 rpm
Torque 78.9 ft-lbs @ 7400 rpm

In other words, 3.7 bhp / 2.9% increase from 15w-50 to 5w-40, a 2.8 bhp / 2.1% increase from 5w-40 to 0w-20 or a 6.5 bhp / 5% overall. Not bad, just for changing the oil! More to the point, a keen bike owner would have paid at least £1000 to see less improvement than this using the conventional approach of exhaust/intake mods, ignition re-mapping etc.

Am I recommending that you use 0w-20 in your Subaru’s? Well, perhaps not! The 5w-40, which is a “proper” PAO/Ester shear-stable synthetic, will look after a powerful engine better than a heavier viscosity “cave at the back” conventional oil, and provide a useful extra few BHP.

The End

However, as with all good things in life, we don’t live in a world of perfect motor cars and therefore we have to look at the lubrication trade-off between longevity, reliability, power and cost, relative to the vehicle in which the oil is being used (a scruffy old XR2i with 192,000 miles on the clock is a very different proposition to your new Impreza). Which is why Subaru (and probably your local dealer) recommends a 5w-40 or 10w-50 (Such as PRO S); you could look at a 5w-40 for competition and track-day use, but only the most committed competitor would want, or need, the 0w-20 for the extra 5% power.


If you got this far then you will have a better understanding of oil and hopefully will understand that there is more to the oil debate than simply oil is oil and it doesn't matter wnat you use.

Cheers
Simon

hoskib

iTrader: (1)

tin, worms, opened

NorthDownsScooby

lock the thread....

<runs for cover>

...lock the thread NOW !!

16vmarc

Lock it?! Top it!!!!

Bubba po

Excellent.

pslewis

Who is the Author .............. and what credentials does he have??

Pete

Can anyone post up Subaru's statement regarding Oil for THEIR car that they developed and spent $MILLIONS on??

Ben v7

Interesting read that.

pslewis

Rick Rhoades
Rick Rhoades joined Subaru of America in 1989 and is currently the Technical Training Instructor for the Pennsylvania/New Jersey region. Over the years he has held various positions within Subaru including Financial Claims Specialist, Technical Service Helpline Specialist, and Field Service Operations Manager.

Rick also teaches part time for the Philadelphia Community College - licensing technicians for Pennsylvania Safety and Emissions Programs.

Pete Eike
Pete Eike joined Subaru of America in 1982 and is currently the National Fixed Operations Training Manager. Over the years he has held various positions within Subaru including National Customer Relations Training Instructor and Manager, and National Service Training Instructor and Manager.

He has conducted over 500 Subaru training classes all over the United States, focusing on the traditional in-class-training environment designed to educate professional service and parts management

Chat Transcript:-

<moderator_kh>: Welcome Rick and Pete. To get things going, what is the one service related question that you get asked the most?

<rick_subaru>: Can I use synthetic oil? And the answer is YES as long as they abide by the regular intervals in the Subaru maintenance booklet

<jmackuliak 4>: That is not what the tech service line told me about synthetic oil?

<rick_subaru>: Do you work at a dealer?

<jmackuliak 4>: Yes. I was told that all seals were not approved for synthetic oil and I may encounter leaks at my own risk.

<pete_subaru>: If you start out with a synthetic, keep using a synthetic... if you start out with a regular oil, and switch, yes you could encounter leaks.

<bratman>: It's time for my WRX's first oil change. How early can I switch to synthetics?

<rick_subaru>: Do it NOW... but stick with it after you make the switch

<bazzal>: RE Synthetic Oils: You say that if you "start out" with Synthetic, stay with it. I have 6500 miles on my LLBean with regular oil. Am I risking problems if I were to switch at the upcoming 7500 mile oil change?

<rick_subaru>: No... But if you switch, stick with it, don't look back!

<kens>: Hi Pete & Rick -- Two oil related questions: 1) What's Subaru's stance on synthetic oil on the Phase I engine? Is it better than conventional oil? 2) What is considered normal oil consumption? I typically loose about 1 quart every 3000 miles or so. No signs of leaks or blue exhaust smoke. Is this something to worry about? I have 70K miles on my 98 Forester.

<rick_subaru>: On the synthetic oil... if you start with synthetic, stick with it. For the oil consumption, 1 quart per 1000 miles is actually acceptable

<michael_desu>: Is that 15W-50W engine oil better for high speed driving? Since I think the engine is going to be very hot...

<pete_subaru>: How fast are you going??

<michael_desu>: When I race, I will go around 6-7000rpm, then shift up.

<rick_subaru>: 15W-50W is usually better for hotter conditions. We don't recommend using it because it has an adverse affect on fuel mileage and emissions. It's not a bad oil to use for your circumstance.

<got_wrx>: I am using Mobil1 10-30W synthetic. I heard this brand/grade could ruin the WRX's engine. Is that true?

<rick_subaru>: No, it should not have any adverse affect on the engine, provided you're putting more than one quart in! LOL

These lads do not have oil to sell, niether do I ................

Take your advice from where you wish - but look at it all with an open mind!!

Pete

Bubba po

They sound really knowledgeable.

pslewis

Just found a brilliant line, shame I cannot take credit for it ......... but it describes what I (and Suabru) feel EXACTLY!!

I quote:-

"Synthetics aren't really needed.

But you do need them if you have a rear spoiler and go faster stripes, they
all work as a team"

-------------------------------

And there I think you have the definative statement ...... if you are a 'Go-Faster RoyBacer' you NEED Fully Synthetic!!

Pete

pslewis

The Web is littered with the same discussions:-

I quote another:-

"If you are going to change to Full synthetic (the stock should be semi-syntehtic anyway), do it sooner rather than later.

Many people have trouble when they change to synthetic later in your engine's life because it will tend to seep oil from everywhere because the mieral oil is good a keeping the seals conditioned better for an older motor.

A sudden change can see a fair few seepages. Or you go to synthetic early on, there should be no problems at all.

Be aware that with full synthetics I would not tend to want to keep that oil in any longer than conventional oil despite what they say (especailly with turbo mtors). The single best things you can do to prolong enigine life is change oil and filters.

For everyday driving I doubt you would notice much difference using full-synths compared to semi-synths (of a reasonable quality).

Except price.

Many arguements for both, but doubt you will get a consensus.

Subaru motors have been known to go well over 350,000km on pure mineral oils. Turbos, obviously need a more technological oil.

Whatever grade or oil type is recommended in the owner's manual is certianly good enough"

Lots of very wise words from those who don't stand to profit one way or another.

Pete

16vmarc

What type of oil do you use Pete? Semi synthetic?

Bubba po

They even say "arguements", which, of course, is the proper spelling despite what other people have found.

Bubba po

He doesn't use Shell Helix semi-synthetic, which is what Subaru recommend.

pslewis

Now, now ................

I use what SUBARU recommend I use ..... no more (waste of good money), no less (would be stupid to risk my engine)

After all, as I keep saying, SUBARU invested $MILLIONS in researching which oil is best.

Pete

16vmarc

Out of interest what grade?

Vegescoob

Me, I use virgin olive oil, sunflower oil, rapeseed oil, cold pressed hempseed oil and toasted sesame oil.
I like to look after those internals, afterall they were developed over a very long time.
Never ever plain "vegetable oil".

pslewis

Shell Helix semi-synthetic was used for the first 11 services .... Comma Semi or Halfords FULLY for the others.

http://www.commaoil.com/Product%20%2...-10w-40-5L.gif

Is my Oil of choice and, incidentally, the local Subaru Independent Mechanic in our area uses this:-

http://www.commaoil.com/Product%20%2...rway-10w40.gif

We buy our Oil at the same Motor Factors, the owner of which has 30 years experience selling Oils (and all kinds of Motor related stuff) .......... he sells many 5 Litre cartons a day. He says that Fully Synthetic preys on the thick, stupid and easily scared!! so, he's at least, honest!!

Pete

Mark_S

"I use what SUBARU recommend I use ..... no more (waste of good money), no less (would be stupid to risk my engine) "


Subaru dont recommend Comma semi.

lordlucan

I think you may find Mr Lewis uses a Comma Semi Synthetic.....Quality oil....

But hey I have just put Halfords Fully Synthetic in my car as it was cheap ! Merely on the basis of regualr oil changes and the fact I never keep cars long !

J

pslewis

Comma's recommendation for Subaru Impreza Turbo:-

http://www.commaoil.com/Product%20%2...-10w-40-5L.gif

Alternative recommendations,

Engine:

MY <2000: <30°C, 5W-30

MY <2000: >-20°C, 10W-40

MY <2000: >-20°C, 10W-50

MY <2000: >-15°C, 15W-40

MY <2000: >-15°C, 15W-50

MY <2000: -20°C to >40°C, 10W-30

MY <2000: -20°C to >40°C, 10W-40

MY <2000: 40°C to <-22°C, 5W-30

MY >2000: <-30°C to >40°C, 5W-30

MY >2000: -20°C to >40°C, 10W-30

MY >2000: -20°C to >40°C, 10W-40

Now, these boys REALLY do know their stuff!!

Pete

pslewis

They don't recommend KY or Vavolene or silkolene or vaseline or motul or Anusoil either ................................

Pete

Bubba po

Why don't you use Shell helix semi-synthetic, Pete? And how can you get 30+ mpg on four 1.5 mile journeys per day?

16vmarc

Shell Helix 5w 40 fully synthetic for me, which incidently is the same consistancy as your 10w 40 once up to temperature

andyr

So Pete, you are choosing to take the word of a salesman as gospel ?
The "local Subaru Independent Mechanic" is an expert is he ?

And you believe that Subaru spent $MILLIONS in researching which oil is best : really ? They invested millions of pounds just on investigating which oil was suited to their engine ?
I think that is probably bolloxx, I'd think it more likely that as their engine is not that different to other engines that they would initially test their engine with an oil of reasonable quality and would quote that specification of oil in the handbook unless they had good reason to do otherwise. I'd be surprised if Subaru have ever gone through dozens of different oils doing long-term tests with each of them and finding no improvement from use of the highest quality oil over the lower quality oils.
For, as you term it, 'extreme' driving style minimum spec. oil will no doubt suffice but other people stressing their engine to a greater degree will be providing their engine with a greater margin of safety with a higher, more expensive oil - the Comma and similar price-point oils MAY WELL BE FINE but the better oils will provide additional protection which for the additional cost many Subaru owners prefer to incurr, as opposed to more expensive engine problems that could result.

Pete, I think unless someone posts on here asking for an oil relevant to purely driving where the engine speed barely exceeds idle then your input is close to worthless.

pslewis

I cannot get that oil as easy as the equally good Comma - Subaru Main Dealer used to charge me £25 for 5 Litres ...... the Comma comes in at £15.

I just get 35+ mpg without trying .........

I reckon it's the skill of the driver? 100% anticipation of the road ahead = no need to use brakes or accelerate = good service life from brakes = excellent mpg figures ...........

It's all sooooo simple really ......

Pete

Bubba po

You can't do it. It isn't possible. You cannot get that mpg with those journeys. Unless you're being towed everywhere. .

pslewis

You really are a pratt from the Premiership of ***** aren't you?

I quoted many words ... which weren't mine you raving lunatic!!

From SUBARU Experts .............. no less

Shut up ......

Pete

pslewis

Try my advice tomorrow, drive like you have a raw egg under the throttle pedal ................... and drive as if you have no brakes whatsoever!

You, too, will see remarkable achievements ......

Pete

Bubba po

You're losing it. Misinterpreting his post purposely... Abusive language... aggressive stance. You are standing on a sticky wicket Pete and you're making yourself look foolish. It's time for your bed.