The author is an australian chemist called RJHUG1 or RHSPECR from Performanceforums and Nissan silvia forums.

These are his words
'OK fair enough, i just hope i dont loose people with the chemistry because i have done that before. Thin oils have thinner characteristics at low temps compared to thick oils - obvisouly. 0w and 5w are both fine. This is good because it means it will circualte with ease at cold temps and start up. The reason why it's good for a turbo is because it allows for better and more efficient spool up. It also gets to oppertional temp quicker. A fluid with a high density has a higher specific heat capacity (with al things being equal) which means it takes longer to store heat. Oils dont like being cold. When the car has warmed up the turbo has not, or not that well i should say. It takes time when the car is on boost for the turbo to get up to temp. Thin oils are quick to respond (matter of seconds) thick oil are not (upto minutes). That time is a killer for turbine wear. But no one here has issues with the lower viscosity (except the 25w dont know what on earth is going on there) So 5w30 is fine for that.

Where the problem comes in is the 30 bit. Its to low. That means the oil molecules will begin to dissociate upon thermal energy past its flow rate. This is oxidation or break down or in my terms the lose of electrons from outer shells in atoms. Therefore when the engine gets hot, the break down of the oil begins to occur and happens quickly. This means its life in the engine is limited. Thicker oils have larger aromatic hydrocarbons and stonger carbon to carbon bonding between the alkanes. Basically its a bigger molecule. Hydrocarbons are just that - hydrogen and carbon molcules and they start off simple gases like methane CH4, to liquids like octane C8H18 up to waxes as high as C80 ect and then into tars. The higher the carbon content the higher the viscosity and the harder it is to break down into simpler forms. We know that butane (C4H10) from a cigi lighter burns easily cause its small but a larger one like petrol (which is a mixture of octane, pentane and hexene) is less volitile and then diesel is less flamable again cause its bigger - feels greezy between the fingers. Gas is better than petrol, which is better than diesel which is better than oil ect...with respect to breakdown or flamability and thus resistance to oxidation.

So....the thicker, the heavier, the more resistant to heat, the longer it lasts. The sr and ej and 4g engines have pretty small sumps and small oils ports. They need something that circulates easily. Presure is related to density and corss sectional area of the passage in which it flows and density is related to viscosity and x-sectional area is related to port size. Sucking water through a straw is easier than sucking honey.

When the temps get to high the 30 oils is out of its range and it starts to become ineffective. I can hunt down some mass spectrocopy plots and titration curves comparing the multigrades we use for different tracks and requirements for the f1 engines. It shows how as temp rises oxdation occurs at a rate of 0.056m/mol per Kelvin. This is for the 'special' oil in the race engines, the trends would be the same in road oils as well.

Also, the stoke on a 2L motor is quiet small. This is why our engines rev to 7000rpm and most pushrods v8 go to 5500. The longer the stroke of the engine the more stress occurs on the bottom end bearing from internal inertia. Like dropping an object from two fifferent heights and each will hit harder depending on height and load (revs). Thin oils find it hard to maintain the thin film lubrcation on bearing when the stress becomes high. So if the engine is working hard for long times or has massive power and or long stroke then the oil needs to become thicker - what resists spreading easier out of grease and wax - both HC's but wax is thicker. Thicker oils resist destortion upon movement.

Hopefully that makes it clearer - but quiet possibly makes it hard to follow but i tried to relate it back in lame terms.

I have no prob in people expressing views ect and their thoughts

Until the days comes when you obtain a major in organic chemistry, work with mobil, win world championshps with mclaren and are asked by subaru and renault f1 to write articles for their race magazine, can i possibly take anything you say with a pitch of salt.

i'am rhspecr

The author is an australian chemist called RJHUG1 or RHSPECR from Performanceforums and Nissan silvia forums.

These are his words
'OK fair enough, i just hope i dont loose people with the chemistry because i have done that before. Thin oils have thinner characteristics at low temps compared to thick oils - obvisouly. 0w and 5w are both fine. This is good because it means it will circualte with ease at cold temps and start up. The reason why it's good for a turbo is because it allows for better and more efficient spool up. It also gets to oppertional temp quicker. A fluid with a high density has a higher specific heat capacity (with al things being equal) which means it takes longer to store heat. Oils dont like being cold. When the car has warmed up the turbo has not, or not that well i should say. It takes time when the car is on boost for the turbo to get up to temp. Thin oils are quick to respond (matter of seconds) thick oil are not (upto minutes). That time is a killer for turbine wear. But no one here has issues with the lower viscosity (except the 25w dont know what on earth is going on there) So 5w30 is fine for that.

Where the problem comes in is the 30 bit. Its to low. That means the oil molecules will begin to dissociate upon thermal energy past its flow rate. This is oxidation or break down or in my terms the lose of electrons from outer shells in atoms. Therefore when the engine gets hot, the break down of the oil begins to occur and happens quickly. This means its life in the engine is limited. Thicker oils have larger aromatic hydrocarbons and stonger carbon to carbon bonding between the alkanes. Basically its a bigger molecule. Hydrocarbons are just that - hydrogen and carbon molcules and they start off simple gases like methane CH4, to liquids like octane C8H18 up to waxes as high as C80 ect and then into tars. The higher the carbon content the higher the viscosity and the harder it is to break down into simpler forms. We know that butane (C4H10) from a cigi lighter burns easily cause its small but a larger one like petrol (which is a mixture of octane, pentane and hexene) is less volitile and then diesel is less flamable again cause its bigger - feels greezy between the fingers. Gas is better than petrol, which is better than diesel which is better than oil ect...with respect to breakdown or flamability and thus resistance to oxidation.

So....the thicker, the heavier, the more resistant to heat, the longer it lasts. The sr and ej and 4g engines have pretty small sumps and small oils ports. They need something that circulates easily. Presure is related to density and corss sectional area of the passage in which it flows and density is related to viscosity and x-sectional area is related to port size. Sucking water through a straw is easier than sucking honey.

When the temps get to high the 30 oils is out of its range and it starts to become ineffective. I can hunt down some mass spectrocopy plots and titration curves comparing the multigrades we use for different tracks and requirements for the f1 engines. It shows how as temp rises oxdation occurs at a rate of 0.056m/mol per Kelvin. This is for the 'special' oil in the race engines, the trends would be the same in road oils as well.

Also, the stoke on a 2L motor is quiet small. This is why our engines rev to 7000rpm and most pushrods v8 go to 5500. The longer the stroke of the engine the more stress occurs on the bottom end bearing from internal inertia. Like dropping an object from two fifferent heights and each will hit harder depending on height and load (revs). Thin oils find it hard to maintain the thin film lubrcation on bearing when the stress becomes high. So if the engine is working hard for long times or has massive power and or long stroke then the oil needs to become thicker - what resists spreading easier out of grease and wax - both HC's but wax is thicker. Thicker oils resist destortion upon movement.

Hopefully that makes it clearer - but quiet possibly makes it hard to follow but i tried to relate it back in lame terms.

I have no prob in people expressing views ect and their thoughts

Until the days comes when you obtain a major in organic chemistry, work with mobil, win world championshps with mclaren and are asked by subaru and renault f1 to write articles for their race magazine, can i possibly take anything you say with a pitch of salt.

i'am rhspecr

Can an oil be too thick?
In essence yes.

The problem with selecting an oil that's too thick for your car is that it wastes power and causes more friction which in turn causes additional heat and wear in the engine.

Here are the figures for viscosity in cst (centistokes) and temperature for different oils.

The first numbers are sae numbers for straight 30,40,50 and 60. The second set of numbers is for various multigrades as they are obviously thinner when cold than straight oils due to lighter viscosity basestocks being used.

Monogrades

Deg. C...........0.....20......40......60......100.. ....120

Sae 30 ....1600....315.....95.......39......11........7 ...
Sae 40 ....2579....473....135.......52......14.......9. ...
Sae 50 ....4592....771....205.......75......18.......11 ..
Sae 60 ....7865...1218...303.......105.....24.......14. .

Multigrades

Deg. C ...............0...............10............40..............100

0W/20............329............181...........46..... ..........9..
5W/40............811............421...........92..... .........14..
10W/50..........1039...........539..........117....... ......18..
15W/50..........1376...........675..........130....... ......18..
20W/50..........2305..........1015..........148....... ......18..

These two graphs demonstrate the fact that a monograde is the same thickness at 100degC as a multigrade of the same sae number but the distinct benefits that a multigrade brings at lower temperatures. This is obviously benefits cold crank wear as the rate of flow of multigrades is much better at lower temps.

There is no temperature where oil suddenly starts to flow better. A 10W/40 for example will flow between -25C and 100C or more, but there is a big difference in the rate of flow (True viscosity at -25C is about 7000 Centistoke(cSt) units, dropping to 14 at 100C. ‘Viscosity’ is just another name for ‘rate of flow’.

The question is, at what (sump) temperature is the oil at a viscosity that suits a modern high-RPM engine.

Present day designs seem happy on an oil viscosity of 10 to 15 cSt. (But many are OK on less than 10.) 30cSt is too high at high RPM. It can lead to foaming, air entrainment and cavitation.

............Temp. for 30cSt (Deg. C).......Temp. for 15cSt.......Temp. for 10cSt

5W/40..................71...........................90........................117...............
10W/40................70...........................99. .......................118...............
10W/50................80...........................109 .......................130..............
10W/60................89...........................119 .......................142..............

This shows that a 5W/40 or a 10w-40 is perfectly adequate for all engines except those that run an unusually high temperatures. In these cases a 10w-50 or 15w-50 may be called for.

Also, a thick oil can lead to trouble unless properly warmed up before high RPM is used.

I hope that these figures at least give some insight to what actually happens to the oil inside your engine at different temperatures.

Cheers
Simon

http://www.skylineowners.com/forum/show ... hp?t=25640

If you're talking Silkolene PRO S 5w-40 then the chemist recommends a maximum temp of 120deG and for PRO S 10w-50 and PRO R 15w-50 140degC.

These oils are race oils and they are built to withstand punishment (as are Motul 300V oils). I have been advised also that unless fuel dilution is a problem they will run to 10 track hours or 9000-12000 road miles.

These oils do not shear (lose viscosity) easily especially if they are used within their limits but addatives do get used up over time.

Cheers
Simon

http://www.gtr.co.uk/forum/upload/32925 ... ine-4.html

Ο άνθρωπος πουλά λάδια by the way, τί το καλύτερο γι'αυτόν από να γράψει οτι θέλουν αλλαγή στα 5000 χλμ.

What Is Normal Oil Consumption?

Oil consumption is normal and necessary for internal combustion engines to run properly. At what level does oil consumption become abnormal, you may ask? This question is difficult to answer since different engine designs may lead to different levels of “normal” consumption.
Picture a car with an oil consumption problem. Most would imagine a car belching a smoke-screen for several blocks. Others might envision a vehicle which leaks a lake of oil on the driveway.
Neither of the above examples describe our typical call relating to oil consumption. The typical car we hear about consumes around 2 to 3 quarts of oil every 3000 miles. Is this normal consumption?
Possibly, but one needs to investigate further.
First, where did the oil go? Oil is lost by either an external or internal oil leak. What may appear to
be a small external loss could actually turn out to be excessive. Did you know that one drop leaking
every minute from an engine would add up to 7 gallons in a year? Also, one drop of oil leaking from
a vehicle every 20 feet would lead to 1 quart of oil lost every 100 miles, which equals 7.5 gallons
every 3000 miles! Since a small leak may often go undetected, it is very important to carefully and
thoroughly investigate external leaks before looking for other possibilities.
External leaks may be due to leaky valve cover gaskets, oil pan gaskets, front or rear main seals or
cracks in the crankcase or valve covers. To make leak detection easier, clean the engine before you
start searching. Using special dyes in the oil may also help identify evasive leaks. Keep in mind that
the evidence of a leak may not be found near the actual source. A clogged or inoperative Positive
Crankcase Ventilation (PCV) system may lead to oil consumption indirectly by increasing crankcase
pressures and forcing oil from the gaskets and seals. Crankcase breather elements, PCV valves, hoses
and related items should be inspected and replaced as needed, or as recommended by the
manufacturer, to prevent these problems. If there are no signs of external oil loss, the leak is probably
internal and will be more difficult and expensive to locate and repair.
Blue smoke exiting the tail pipe signals an internal oil consumption problem. Even if blue exhaust
smoke is not apparent, internal oil consumption may still exist. If an engine burns as much as one
drop of oil on every firing stroke it will use more than a quart of oil every two miles! The most likely
sources of internal oil consumption are worn valve guides and worn piston rings. If you think you
have an internal oil consumption problem, check with your local mechanic about performing a
leakdown test, a compression test or a ring seal (blow-by) test. A qualified mechanic will use these
tests to pinpoint the source of internal oil consumption. Other possibilities of internal and external
consumption are listed below.

Internal Oil Consumption
Improper oil levels, Valve cover gaskets
Incorrect engine oil viscosity, Oil pan gasket
Clogged PCV System ,Front and rear main seals
Worn valve stems and guides, Cracks in the crankcase
Worn, broken or stuck piston rings, Leaking oil drain plug
Improperly installed piston rings, Porous crankcase casting
Worn ring grooves, Cylinder Head Gasket
Cracked or broken piston lands
Incorrect pistons
Improperly honed cylinders
Distorted cylinders
Worn or damaged main bearings
Worn or damaged cam shaft bearings
Bent or misaligned connecting rods
Excessive oil pressure
Blown cylinder head gasket
Clogged oil passageways
Fuel dilution of the engine oil
Clogged crankcase breather element
Intake manifold leak

External Oil Consumption
Valve cover gaskets
Oil pan gasket
Front and rear main seals
Cracks in the crankcase
Leaking oil drain plug
Porous crankcase casting
Cylinder Head Gasket

An increase in oil consumption is most likely due to a combination of several of the above items.
Also, oil loss can be masked by other conditions such as fuel dilution. In this case, the fuel will
evaporate if the vehicle is driven under highway conditions for an extended period of time giving the
appearance of excessive oil consumption. In reality, the drop in oil level was a result of a change in
operating conditions and evaporation of the fuel in the oil.
Steps to Identify Abnormal Oil Consumption

1. Consider the year and model of vehicle, the type of engine, the type of service the
   vehicle is driven in and how the engine was maintained.
2. Was there a drastic change in consumption? A part may have broken.
3. Were there recent changes in operating conditions?
4. Check for external leaks. Small leaks can lead to big losses.
5. Then, check for internal leaks.
   Obviously, most engines begin to consume more oil as they wear. We recommend three basic steps
   to minimize oil consumption for the life of your car. First, provide proper preventative maintenance.
   Next, use a quality motor oil meeting your automobile’s manufacturer’s specifications. Finally,
   change the oil and filter every 3000 miles or three months, whichever comes first. There is no way to
   completely eliminate all oil consumption. In fact, that would be harmful for an engine. Problems
   with oil consumption can be greatly reduced, however, by following the above advice.
   To keep your Technical Manual current file in Section G: General. This bulletin supersedes
   Technical Information Bulletin G-01 which should be removed and discarded.
   Jack Snavely
   Technical Service Representative, Penzzoil

Having worked in the oil business for a major oil company for all of my adult life, testing, comparing, blending and developing lubricants for major engine manufacturer, I can tell you that a good brand of mineral oil is all an engine requires. There is nothing wrong with high-end (price) synthetic but for most normal application, you are wasting your hard-earned money. I must say the oil comanies have done an extremely good job at marketing their high prices synthetic oil on with they make a very high profit margin.
I sometime compare using synthetic oil in a engine to washing your car with chirurgical certified grade distilled water. It does the job, but at what price?
JackD

http://www.mercedesshop.com/shopforum/s ... hp?t=85971

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We have been doing heaps of tests on oils recently, as we have set up a test using a head in a jig tied into a lathe. The head is then spun at 6000rpm with a syrenge set up on a timer to periodically drop 20ml of oil on the the cam lobes with the test performed for 20mins on each oil.** The cam and all related valvetrain** is then swapped for another set of new gear so we can gauge exactly what each oil is doing. The tests we are doing are a little crude as compared to full laboritory testing but funnily enough castrol has been sending us samples of new oils they are releasing, initially i think to see if we knew what we were doing but now as a secondary source of info.

The problem is each year oil companys are under stricter and stricter regualations on emissions which means they are removing good minerals and chemicals that prelong engine life and stop engine wear.

It has been very interesting to see what some of the oils have done under the testing.** Synthetics are generally half as good as even the cheapest mineral oil,** but alot of cars must run synthetic for the weight properties(π.χ το χειμώνα). I dont want to bad mouth any oils and I wont but from our tests, if you want a good synthetic oil for your car run a motor bike oil like motul or repsoil. The oil for motorbikes doesnt need to meet emissions testing and it it designed better as in a bike it has to be under more loads as the gearbox uses the same oil. About the closest to these in terms of performance in our testing would be redline synthetic, and motul 300. There are few good other ones but these few I have mentioned are easily available to most of you guys.

Hope this helps

http://www.skylinesaustralia.com/forums ... try1640996

http://www.machinerylubrication.com/art ... brication2

http://www.machinerylubrication.com/art ... ilAnalysis

From a performance standpoint, improved purity means that the base oil and the additives in the finished product can last much longer. More specifically, the oil is more inert and forms fewer oxidation byproducts that increase base oil viscosity and deplete additives.

Ο χρήστης mesastou έγραψε:

Περίεργο αυτό από skylinesaustralia πως τα συνθετικά είναι χειρότερα απο τα ορυκτέλαια!

Και όχι μόνο, τα ίδια γράφει και ο χημικός-επικεφαλής της silkolene john rowland.

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(πολύ φοβάμαι οτι εκτός ακριβών και αγωνιστικών λιπαντικών , οι κατασκευαστές βάζουν ελάχιστη ποσότητα εστερικών ενώσεων ή και καθόλου) .
The esters assist load carrying, reduce friction, and cut down seal drag and wear, whilst the PAO’s act as solvents for the multi-grade 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 carbonize in turbo bearings even when provoked by anti-lag systems.

Όσο για το αυστραλέζικο site:

Ο ίδιος ποιο κάτω γράφει 'There synthetics were better than alot of the others but still not what you would want for the price you pay'

Στη θέση του there πρέπει να βάλεις το their και αναφέρεται στην castrol.

Αυτή η καθυστέρηση είναι χαρακτηριστικό γνώρισμα των λεπτών λαδιών. Καλύτερη-ταχύτερη κυκλοφορία που συντελεί στη ευκολότερη απαγωγή της θερμότητας. Επίσης μπορείς να φανταστσείς το λιπαντικό σαν μονωτικό μέσο, το παχύτερο δημιουργεί ,οριακά έστω, ένα παχύτερο στρώμα που παγιδεύει τη θερμότητα.