Oil labelling explained

[oilman]

In our opinion you dont need to go anything thicker then an SAE50.

Cheers

Simon.

[jko]

Just wanted to add this article from How Stuff Works dot com.

Howstuffworks "What does the weight mean on a can of motor oil?"

What does the weight mean on a can of motor oil?

On every bottle of motor oil there is a seal that gives you three pieces of information:

* The API service rating
* The viscosity grade
* "Energy Conserving" indicator (it either is or it isn't)

The API service rating is a two-letter rating that tells you the type of engine the oil is meant for (gasoline or diesel) and the quality level.

The viscosity grade (for example, 5W-30) tells you the oil's thickness, or viscosity. A thin oil has a lower number and flows more easily, while thick oils have a higher number and are more resistant to flow. Water has a very low viscosity -- it is thin and flows easily. Honey has a very high viscosity -- it is thick and gooey.

The standard unit used to measure viscosity is the centistoke (cSt). According to the Automotive and Industrial Lubricants Glossary of Terms:

Viscosity is ordinarily expressed in terms of the time required for a standard quantity of the fluid at a certain temperature to flow through a standard orifice. The higher the value, the more viscous the fluid. Since viscosity varies inversely with temperature, its value is meaningless unless accompanied by the temperature at which it is determined. With petroleum oils, viscosity is now commonly reported in centistokes (cSt), measured at either 40°C or 100 °C (ASTM Method D445 - Kinematic Viscosity).

The centistoke rating is converted into the SAE weight designation using a chart like the one shown on the Superior Lubricants Web site.

Multi-weight oils (such as 10W-30) are a new invention made possible by adding polymers to oil. The polymers allow the oil to have different weights at different temperatures. The first number indicates the viscosity of the oil at a cold temperature, while the second number indicates the viscosity at operating temperature. This page from the Sci.Electronics.Repair FAQ offers the following very interesting description of how the polymers work:

At cold temperatures, the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up, the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. The result is that at 100 degrees C, the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot.

[oilman]

It must be an American article or site as it does not mention the European ACEA specs that appear on European oils.

Cheers
Simon

[iceager]

Some nice info from Simon that needs to be in this sticky.

The figures are here, between 90 and 120degC tops, at 70degC its 30cst which is thick when 10cst to 15cst is a good thickness for a modern turbocharged engine.

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

5W/40..................71...........................9 0........................117...............
10W/40................70...........................99. .......................118...............
10W/50................80...........................109 .......................130..............
10W/60................89...........................119 .......................142..............

Cheers
Simon

[Monster GT-R]

Some of the guys I hang with, are on the band wagon about how full synthec is better then Semi synthetic, and how they don't have to change their oil until they get to 9,000 km. They also use the the arguement that if they go that long they are coming out monitarily the same as the guys on the band wagon supporting semi synthetic who change out at 4,000 km. The full synthetic is much more expensive to buy than the semi, around twice $$$. Also I have a question, on do you use different oils in summer than winter. Here we can get minus temperatures in winter and 28 - 35 in summer. I personally like the semi synthetic's my self. (0W-30)

[oilman]

Synthetics can and will last longer then mineral based oils, they will also do a better job when they are in there. However there must be some confusion, the 0w-30 you use is synthetic. All 0w oils are synthetic.

Cheers

Guy.

[Monster GT-R]

I don't know about over there but here in canada we have blended oils on the menu as well. They are made by Mobil, Esso,Petrocan and one other that I'm having a brain freeze on (Shell maybe). They are only made by the companies that have the refineries. In a couple of lubrication courses I took for work, I was told that the blended mineral and symthetic was superior to just synthetic, you could change the oil later than the mineral oil but before the synthetic. They told us that mineral oil, has various length lubrication molecules. All oils that are run in engines, the lubrication molecules and the polymers get sheared over time. If you had a full synthetic oil (which is made from all the same length molecule), over time it also gets sheared and your base lubricant would thin below it's original viscosity and leave a poor ( more Poor compared to mineral oil) film in the load bearing zones. Poor of course being relative ! If You had a blend of synthetic and mineral oil then the various length lubricant molecules in the mineral oil, would make up for the shearing of both synthetic and mineral. The mineral oil had longer lubrication molecules and could afford some shearing. The synthetic portion added it's benefits to the blend. Oh yeah, the mineral portion performed better in the inital start up, drained bearing and no oil pressure load protection (you know what I mean) than the synthetic, which relied on the polymers to keep it thick when cold. If the polymers were sheared to some degree then the full synthetic would not get to it's designed cold viscosity.

This forum stuff is new to me and it's amazing how long this gets compared to a verbal converstion. The information exchange is really hard here. I've been really sick this week, does any of this make sense?

[oilman]

Not true, the fact is quite the opposite.

Synthetics, proper ones are better for the following reasons:

Stable Basestocks

Synthetic oils are designed from pure, uniform synthetic basestocks, they contain no contaminants or unstable molecules which are prone to thermal and oxidative break down.

Because of their uniform molecular structure, synthetic lubricants operate with less internal and external friction than petroleum oils which have a non-uniform molecular structure. The result is better heat control, and less heat means less stress to the lubricant.

Higher Percentage of Basestock

Synthetic oils contain a higher percentage of lubricant basestock than petroleum oils do. This is because multi-viscosity oils need a great deal of pour point depressant and viscosity improvers to operate as a multigrade.

The basestocks actually do most of the lubricating. More basestocks mean a longer oil life.

Additives Used Up More Slowly

Petroleum basestocks are much more prone to oxidation than synthetic oils. Oxidation inhibitors are needed in greater quantities in petroleum oils as they are used up more quickly.
Synthetic oils do oxidize, but at a much slower rate therefore, oxidation inhibiting additives are used up more slowly.

Synthetic oils provide for better ring seal than petroleum oils do. This minimizes blow-by and reduces contamination by combustion by-products. As a result, corrosion inhibiting additives have less work to do and will last much longer in a synthetic oil.

Excellent Heat Tolerance

Synthetics are simply more tolerant to extreme heat than petroleum oils are. When heat builds up within an engine, petroleum oils quickly begin to burn off. They are more volatile. The lighter molecules within petroleum oils turn to gas and what's left are the large molecules that are harder to pump.
Synthetics have far more resistance as they are more thermally stable to begin with and can take higher temperatures for longer periods without losing viscosity.

Heat Reduction

One of the major factors affecting engine life is component wear and/or failure, which is often the result of high temperature operation. The uniformly smooth molecular structure of synthetic oils gives them a much lower coefficient friction (they slip more easily over one another causing less friction) than petroleum oils.

Less friction means less heat and heat is a major contributor to engine component wear and failure, synthetic oils significantly reduce these two detrimental effects.

Since each molecule in a synthetic oil is of uniform size, each is equally likely to touch a component surface at any given time, thus moving a certain amount of heat into the oil stream and away from the component. This makes synthetic oils far superior heat transfer agents than conventional petroleum oils.

Greater Film Strength

Petroleum motor oils have very low film strength in comparison to synthetics. The film strength of a lubricant refers to it's ability to maintain a film of lubricant between two objects when extreme pressure and heat are applied.
Synthetic oils will typically have a film strength of 5 to 10 times higher than petroleum oils of comparable viscosity.

Even though heavier weight oils typically have higher film strength than lighter weight oils, an sae 30 or 40 synthetic will typically have a higher film strength than an sae 50 or sae 60 petroleum oil.

A lighter grade synthetic can still maintain proper lubricity and reduce the chance of metal to metal contact. This means that you can use oils that provide far better fuel efficiency and cold weather protection without sacrificing engine protection under high temperature, high load conditions. Obviously, this is a big plus, because you can greatly reduce both cold temperature start-up wear and high temperature/high load engine wear using a low viscosity oil.

Engine Deposit Reduction

Petroleum oils tend to leave sludge, varnish and deposits behind after thermal and oxidative break down. They're better than they used to be, but it still occurs.

Deposit build-up leads to a significant reduction in engine performance and engine life as well as increasing the chance of costly repairs.

Synthetic oils have far superior thermal and oxidative stability and they leave engines virtually varnish, deposit and sludge-free.

Better Cold Temperature Fluidity

Synthetic oils do not contain the paraffins or other waxes which dramatically thicken petroleum oils during cold weather. As a result, they tend to flow much better during cold temperature starts and begin lubricating an engine almost immediately. This leads to significant engine wear reduction, and, therefore, longer engine life.

Improved Fuel Economy

Because of their uniform molecular structure, synthetic oils are tremendous friction reducers. Less friction leads to increased fuel economy and improved engine performance.
This means that more energy released from the combustion process can be transferred directly to the wheels due to the lower friction. Acceleration is more responsive and more powerful, using less fuel in the process.

In a petroleum oil, lighter molecules tend to boil off easily, leaving behind much heavier molecules which are difficult to pump. The engine loses more energy pumping these heavy molecules than if it were pumping lighter ones.
Since synthetic oils have more uniform molecules, fewer of these molecules tend to boil off and when they do, the molecules which are left are of the same size and pumpability is not affected.

Synthetics are better and in many ways, they are basically better by design as they are created by chemists in laboratories for a specific purpose.

Cheers
Simon

[Monster GT-R]

Thanks for straightening me out. Would you suggest a full synthetic OW-40 or a OW-30 Oil the for a high strung (just under 900 HP) RB26DETT engine?

David

[oilman]

Just under 900hp I would look an ester/pao synthetic (a proper one) like Motul 300V or Silkolene Pro S and around 10w-50 or 15w-50 in viscosity

Cheers

[GE1988]

What would you reccomend for my r33 gtr, it has no additional mods? 10w 40 i was thinking of?

[oilman]

5w-40 synthetic is generally what we would recomend.

Cheers

Guy.

[whoflungdung]

Good afternoon Mr Oil Man

I am currently running as per what you said/supplied me Silkolene Pro S 10/50
What are your thoughts on slick 50???
I would be very interested to know

Cheers

John

[oilman]

Our views are here on our website

http://www.opieoils.co.uk/pdfs/A-WOR...-ADDITIVES.doc

Don't waste your money!

Cheers

[whoflungdung]

Ah, so I wont put it in then