Mineral vs Synthetic oil
 

Are synthetic oils any better than mineral oils?

I thought this would be of interest as It's probably the question I get asked the most.

Shame the answer isn't simple though!

The basic benefits are as follows:

Extended oil drain periods
Better wear protection and therefore extended engine life
Most synthetics give better MPG
They flow better when cold and are more thermally stable when hot
For synthetic oil containing esters - esters are "surface-active" meaning a thin layer of oil on the surfaces at all times

If you want to know the reasons why then please read on but, warning - Long Post!

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 its 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.

In practice, the fuel economy benefits might be pretty marginal though!

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.

Hope this helps!
- Guy

Interesting stuff oilman. Can you talk about semisynthetics too? That would be useful.
Ta!

Sure, what would you like to know about them?

Cheers

Guy

Would you go for fully synthetic rather than semi?

What are the pros and cons of semi synth, compared to fully synth?

Depends on what type of clutch you have- dry or wet -
My Dakar has a multi-disc oil-bath clutch, mechanically operated and I use Silkolene semi-synth whereas the R1200GS has a single plate dry clutch hydraulically operated- I use a Castrol fully synthetic in that.

It is the additives in some of the fully synthetic oils that can cause wet clutch bikes to slip. I do not know what type of clutch the Africa Twin has.

The more synth you have, the better it is, surely ? :)

I remember attending a seminar held by Shell about motor oils and from what I remember (it was a few years ago now), synthetic oils are pretty much better in every way than mineral oils. Obviously, apart from cost.

I always use semi-synth as for me its the best compromise between cost and efficiency.

Yes, I would go for synthetic over mineral, mainly becuase they are better, but not all synthetics are synthetic in the true sense of the word many are modified mineral oils sold as synthetic.

Cheers

Guy

Thanks - I didnt know that semi was classed as mineral.

Can you tell me this? - if I buy a cheaper m/cycle oil with the correct JASO/SAE codings, will it be as good as an oil twice the price?
In other words, is brand important? Can an oil be inferior if the codes are right?

Depends, yes mainly with oils you get what you payfor so an oil twice the price is likely to be better.

Also think of it this way, one oil may just be good enough to meet a JASO spec, another oil can also meet that spec but also exceed it by a long long way, but there is now spec to show this it will just show up as meet the same JASO spec.

Cheers

Guy

What are the differences, between mineral, semi-synthetic and fully synthetic oil?
 

Here's a bit more info on the topic from our friend John Rowland, the chief chemist at Silkolene....

"
Before we get into details, the first thing to realise that there is no chalk and cheese difference between mineral and synthetic based oils. After all, the chemical compounds which make mineral engine oils so much better are themselves synthetic. Synthetic lubricant bases are stepwise improvements on mineral oil, with more desirable properties and fewer undesirable ones.

The second important point is that there's no one thing called 'synthetic'!

There are several different types of synthetic lubricant, and to say something like: 'the Supergrunt XXR must have a full synthetic' is meaningless unless the 'expert' explains what sort of synthetic he means.

Equally, to imply that dreadful things will happen if the 1970 Hardley-Ableson Bluegrass is run on anything other than Pennsylvania mineral is ridiculous. It may not need a 2007 synthetic, but it isn't going to come to any harm if the owner uses a 2007 synthetic. The most basic type of synthetic is really a special mineral oil.

Known as 'hydrocracked' bases, these are made in oil refineries by putting certain types of mineral fraction through special processing, so they cost more than the usual mineral types but not much more. They are useful because they resist evaporation at high temperatures. Although used for years for genuine technical reasons, they are now popular with marketing men because the magic sexy word 'synthetic' can legitimately be printed on the label without spending much on the oil inside the can! Yes, all low-cost 'synthetics' contain anything from a few percent to 20 percent (i.e. 'semi-synthetic') of special mineral oil.

Using fairly simple chemical compounds or gases from oil refineries or other sources, it is possible to 'synthesise' or build up tailor-made lubricant molecules which have very desirable characteristics, such as great resistance to cold, heat, evaporation losses or excessive thinning as they get hot. These are the true synthetics, and the two that are used in engine oils are PAOs (poly alpha olefins) and esters. Neither is cheap!

PAOs are related to mineral oils, and are the ideal carriers for all the chemical compounds used in mineral oils. Because they do not gel at very low temperatures, all genuine 0W-something oils have to be based on PAOs to pass the 0W test at a sub-arctic -35C. Esters were originally made for jet engine lubricants, and to this day all jet oils are ester-based. Although similar in performance to PAOs, they have a valuable extra trick: they are good lubricants and help to protect metal surfaces.

As 0W- and 5W- grades are not usually recommended for motorcycles, perhaps the best all-round oil is a 10W/40 shear-stable semi-synthetic with some ester content.

Esters help with transmission and valve train lubrication. 100% fully-synthetic oils are actually quite rare, probably because they are very expensive to make, and even more expensive to buy.

Even so, an ester / PAO with a very shear stable multigrade polymer is the ultimate oil for high output engines that are worked hard, which means racing.
"

All good stuff

Cheers

In Europe, provided the price hasn't been pushed up by shipping an "average" oil 5000miles from the West coast of the USA, you do get what you pay for. The best motorcycle oils are made in the more developed European countries, but low price buys the cheap 'modified mineral' synthetic and not much of it, with a poor multigrade polymer. As is so often the case, quality does follow cost.

Thanks for posting all this very interesting info. I, for one, appreciate it.:thumbup1:

My Honda asks for a minimum SG quality oil. I found a 10/40 supermarket semisynthetic motorcycle oil which is rated SJ - which is above this minimum. This oil costs 4 euros (£3-ish) a litre. But I don't know if it contains the ideal additives mentioned by the Silkolene man. He suggests a semisynth, but of quality. How do I know it's quality? It seems the answer is cost.

I'd better start hunting for another oil? Do we get value for money from the big names, or are they cashing in on a name?

Problems problems!!!!

Well, with oil you get what you pay for and it's what's not in the oil that matters as addative packs vary in quality too. Many oils are made to a budget because in many applications it does not matter, afterall "any oil is better than no oil".

The problems tend to start with wet clutches and many cheaper oils (mainly car ones as opposed to proper bike ones) do not contain the correct additive pack and may contain friction modifiers which may cause slippage in the wet clutch.

If your bike has a wet clutch go for a bike oil that carries the correct JASO spec as it's designed for Japanese Motorbikes.

These are Japanese and International stanadards for Japanese bikes, I would personally always use a proper bike oil, more stable and contains the correct ingredients.

http://www.opieoils.co.uk/c-773-motorcycle-oils.aspx

A semi-synthetic for ordinary road use and a fully synthetic if modified, used hard or off the road.

Cheers
Simon

Check out the following link for oilman's previous sales pitches.

oilman uniform synthetic basestocks - Google Search

Oilman
Registered Vendor
HUBB regular

Yes, but all this is the same typical sales talk. It is many times proven that things that are most expensive in their segment do not usually offer the best (or even near the best) price/performance ratio. :nono:

Where are independent test results that compare different oils? I'll start buying expensive full synth oil if I see proof that the cost is justified.

So this is all very interesting, and I'm enjoying learning a bit about motor oil formulations. Yes but however.....

Obviously, I don't need "friction modifiers" to keep my wet clutches from slipping. They don't slip. They've never slipped. I'd be willing to bet cold hard cash that they won't ever slip....until past their wear specifications, at least....and I've used all sorts of oils, at all sorts of price points, in all sorts of circumstances all over three continents. So in the absence of information more compelling than a vendor's statement that I need friction modifiers because "many cheaper oils (mainly car ones as opposed to proper bike ones) do not contain the correct addative pack and friction modifiers to stop the wet clutch slipping," I think I'll pass. And while I'm at it, I might as well pass on the rest of the advice in the same posting--either you've got credibility when making unsubstantiated assertions, or you don't.

The paste from the oil chemist is a whole different story. He sounds believable throughout (although I have to ask how fundamentally important are the marginal benefits he's describing), but this leads me to wonder: how would I recognize "a 10W/40 shear-stable semi-synthetic with some ester content" if I stumbled over it? It's the reported shear-resistance of the Rotella synth (reported by folks on another forum who routinely send their used oil out for testing after each oil change) which convinced me to use it regularly when I'm in this country. How would I know what else to use?

I can't even believe I'm participating in an oil thread! What came over me? How will I regain my former highly-prized state of aloofness?

Mark

Oilman...

You obviously know your stuff :thumbup1:


Can you explain multigrade oil ??? 10W40 vs 15W50 etc ??

What does the W exactly stand for... Some say its the weight some swear it means "winter" etc etc.

I thought that a 10W40 will act like a nice easy flowing 10W when its cold and only get as thin as a 40W when hot ! Am I right ???

As I understand it its the other way round.

Car oils have friction additives because the engine and clutch are house eperately, as is the gearbox. The engine needs low friction, the gearbox needs shear resistance and the clutch needs, well nothing.

In motorcycles there are no such friction additives because most bikes have engine, box and clutch all bathed in the same oil. So the friction modifiers would not stop your clutch from slipping but would, in fact, make it more likely to slip, particularly if the clutch is starting to reach service limits.... that limit may be brought forward with car oils...

Hence why car oils in a wet clutch bike are best avoided, plus the fact that a car oil is probably not designed to deal with a gearbox thrashing about

That is my understanding...

Oilman, come back to me!

I've checked my semisynthetic motorcycle oil specs. I have on the can :

API SJ
JASO MA
SAE 10W 50

In theory, this cheap(er) oil exceeds the needs of my Honda which asks for SG. I've read your posts, and this seems to be the case.

Can the oil seller lie to me (in Europe), and sell me chip fat repackaged:eek3:? There's so much consumer distrust around that oil threads get like this, as you see above.:confused1:

Yes of course no problem...............

If you see an expression such as 10W-40, the oil is a multigrade.

This simply means that the oil falls into 2 viscosity grades, in this case 10W & 40.

This is made possible by the inclusion of a polymer, a component which slows down the rate of thinning as the oil warms up and slows down the rate of thickening as the oil cools down.

It was first developed some 50 years ago to avoid the routine of using a thinner oil in winter and a thicker oil in summer.

For a 10w-40 to attain the specification target a 10W ( W = winter) the oil must have a certain maximum viscosity at low temperature. The actual viscosity and the temperature vary with the viscosity grade but in all cases the lower the number, the thinner the oil, e.g. a 5W oil is thinner than a 10W oil at temperatures encountered in UK winter conditions.

This is important because a thinner oil will circulate faster on cold start, affording better engine protection.

For a 10w-40 to attain the other specification target a 40 oil must fall within certain limits at 100 degC. In this case the temperature target does not vary with the viscosity grade, if there is no "W", the measuring temperature is always 100degC. Again the lower the number the thinner the oil, a 30 oil is thinner than a 40 oil at 100 degC., which is typical of maximum bulk oil temperatures in an operating engine.

The engine makers are, of course, very well aware of this and specify oils according to engine design features, oil pump capacities, manufacturing tolerances, ambient temperature conditions etc. It is important to follow these guidelines, they are important and are an are stipulated for good reasons.

If the engine has been modified, the operating conditions may well be outside the original design envelope. The stress on the oil caused by increased maximum revs, power output and temperature may indicate that oil of a different type and viscosity grade would be beneficial.

Cheers

Those specs look fine to me, if it works for your bike stick with it. I believe that the correct grade should be 10w-40 although check your handbook on this.

Cheers

Maybe I wasn't clear that I was quoting Oilman, who stated that it is the absence of friction modifiers in car motor oil which makes it unsuited for bikes?

Three points: First, some car oils have friction modifiers. As far as I can tell, they are labeled as such ("High mileage" is one warning sign) and are more expensive. They're not appropriate for use in wet clutch bikes. Most car oils do not have these friction modifiers, and are suited, in this respect at least, for use in wet clutch bikes.

Second, empirically speaking (this means based on direct observation, not on theory or confident statements made by unknown persons on the internet), cheap car oils do not cause clutch slippage. There may or may not be other problems related to any or all of their properties, but clutch slippage is demonstrably not one of them. Of course, if someone's got actual experience contrary to mine, I'll listen; this would be someone who can say "I used this cheap motor oil with no special friction modifiers touted on its label in my bike and the clutch started slipping."

Third, it is true that wet clutches and bike transmissions impose harder and more complex working conditions on oils than would normally be found inside automotive engines. There are motorcyclists who track oil degradation by having their used oil tested by commercial testing centers after each oil change. They report on various brands and conditions of use. The consensus on a forum devoted to KLR's is that, for example, Valvoline products tend to degrade rapidly due to polymer shearing; Rotella products (especially Rotella synthetics) generally fare better, and at an excellent price point. But in any case, shearing exists, and it happens rather rapidly The consensus suggests oilchanges by (or sometimes before) every 2000 miles for this reason.

That's all I've got to go on: general understanding of the principles involved, direct personal experience, and the experience of those who take a far more rigorous and analytical approach than I (and have the test results to back their assertions).

Beyond this what's left? Lots of people with lots of opinions--some stated very compellingly but without any supporting evidence....or at least, without any supporting evidence to which I've got access. For me, statements made with passion and/or conviction don't really carry much weight unless also congruent with experience and backed with some sort of evidence.

Your mileage, on the other hand, may vary.

Mark

You're right! slip of the keyboard, 10w- 40 it is!
Of course I'll never know if it works for my bike - that needs science/engineering.

Thanks!:thumbup1:

One interesting side note from BMW F800GS Rider's Manual (2nd ed, 2008, page 126), quote:

"Oil grades: Mineral oils of API classification SF through SH."

It is interesting to note that there is no mention of semisynth or synthetic oils.

Mark, You are of course right. The original post was ambiguously worded and I've gone back to it and amended it:

"The problems tend to start with wet clutches and many cheaper oils (mainly car ones as opposed to proper bike ones) do not contain the correct additive pack and may contain friction modifiers which may cause slippage in the wet clutch."

Guy

Someone else doing some digging on bike oils...
 

I found this informative article whilst looking for something else and thought it might be of interest to you folk:

http://www.calsci.com/motorcycleinfo/Oils1.html

It was written a couple of years ago and a few of the links towards the bottom are broken, but it's well written and an interesting read. Well, interesting if you're interested in oil ;-)

Cheers
Guy

Oilman, just to say thank you for an interesting and useful posting.
Thanks for taking the time.

+1 on the thanks to Oilman.

Another question: As a lubricants guy how do you decide your oil is worn out?

I'm from an automotive design background (not engines) and have sat through meetings where conversations have taken place certain vehicle OEMs would probably not want to talk about. They work along the lines that the engineers have done their testing and concluded part X needs a re-lube every five years and spares should come with a sachet of grease. There is then a conversation with the OE sales guys wanting it to be maintenance free and the parts/service guys wanting it done every ten minutes using grease they can buy in ten gallon tubs. Someone then points out the three year service is a little light, so that box gets a little dot in the box in the service manual.

Then there is Triumph who the day after the 6000 mile oil change Harley Sportster was launched, sent me a new service book for my Bonneville raising the oil change from 4000 to 6000 miles.

Finally there are various old boys on Enfield chat rooms and the like who change their oil every 200 yards.

I stick to the distances in the manual on the basis the OEM must have picked a distance in the right ball park and too frequent changes involve those few seconds running with the oil light on. I change sooner if there is water in there or it starts to look black.

What does the oil and lubes guy do on his own bikes?

Cheers

Andy

Well, oilmans bike is a 1912 Royal Enfield waiting restoration so not using any oil at the moment.

Oil life depends on many factors, the type of oil used (quality), The use of the vehicle and the time the oil has been in the vehicle. Most handbooks will give a guide for normal standard use and mileage and follow those and all will be fine. Once you start messing around with different oils, track time, modifications to the engine (more power) then the rules change.

Cheers

Guy

I have the same 650cc rotax engine in my X-Challenge (and same clutch) and use ONLY full synthetic oil. (have done since the 10,000km mark)

As long as you use a motorcycle specific synthetic oil rather than a car synthetic oil, you will not get any clutch slip. A motorcycle synthetic oil is, after all, specifically designed for wet clutches!

The BMW manual says only that they do not recommend synth oils ONLY for the first 10,000k. I now have 50,000k on my engine, had it pulled apart a couple of weeks ago to check the head, and the mechanics actually asked me if it was a new cylinder. After 50,000k it still had that factory honed look.

For whats its worth, I took the advice of an excellent bike mechanic and use only Motul 300V (double ester) ... its expensive (10 quid a litre in the UK), but you have a several thousand dollar investment and you pour thousands more of dollars of fuel into it over its lifetime. There is only one thing that protects it from wear all its life, and that is the oil. Spend a couple more bux and get a good oil.

Oilman ... is this your site?

Motul 300 V 4T Factory Line 10W-40 Racing lubricant for race bikes 100% Synthetic – Double Ester

If so, I shall be buying form you in the near future.

That's us. Good post and well put

Cheers
Guy

Nice post Oilman.

I'm using full synthetic in my VW diesel and BMW car and have just switched over to synthetic in my R1200GS after the 10,000 km recommended by BWM. My R100GS has had nothing but dino oil in the engine and mostly synthetic in the transmission. The reason I stuck with dino oil is that I thought it would be more practical to do more frequent oil changes in developing countries where synthetic is not readily available. What would you suggest for a trans-Africa journey? Run synthetic as long as possible and then swap out to whatever is locally available, carry enough oil for a change half way down or simply run dino oil from the start, changing as often as practical?

I think we've all heard stories of synthetics causing more oil leaks in an older engine that has grown up on mineral oil. What is the current state of affairs with synthetics? Would putting synthetic in my 230,000 km R100 cause the pushrod tube seals to start leaking?

I like it here..[bear with me]
 

This is why I like the info that comes through Horizons - people are driven by the necessity of high mileages and the inconvenience of cost. A perfect situation to find out, practically at least, what works and what doesn't.

The average annual mileage of motorcycles in the UK is something like 1 or 2 minor service intervals and model ownership is probably a couple of years. So it stands to reason that the average post about oil/observed failure on any given forum has such a biase due to low mileage experience as to render its validity entirely questionable and highly influenced by the statistical 'bathtub' curve of mechanical failure (e.g. bad day at the factory etc.) than any real difference between one motorcycle oil and another.

What do you lot think? I sense an 'elephant in the room'.

The stories about leaking seals are based on older synthetics, not modern ones, so no need to worry about that. The only other reason for a synthetic to leak more is that if the engine has not been particularily well looked after and there is a lot of wear. If the synthetic is thinner than the mineral oil, there may be some leakage.

If you are worried about that, go for one of the hydrocracked synthetics, something like the Silkolene Comp4 or Motul 5100 as they are highly refined and modified mineral oils.

Cheers

Tim