oilman

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
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 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

bud-weis

posted in good time just before ford fair

i ordered 2 bottles of silkolene pro s the other day mate, i got them yesterday thankyou very happy with the service as usual

Christian and Beccy

iTrader: (14)

Silkolene's Techy Info always makes for interesting reading, and timely too as I was wondering the actual reasons for using Fully Synthetic!

James

[start possible wives tale]i was told that yopu shouldn't use semi or fully synthetic in a old engine [e.g. kent crossflow] or any engine that uses cork gasket as the oil eats the gaskets which then leads to blocked oil ways[/end possible wives tale]

bullshit?

Reason being i've re-built my kent engine and have intended to run it on 15/40 magnetic. However i'd rather go down the sythetic route if it's going to give better protecion?

Zetec Andy

I have recently done an oil chnage on my 1.6 Zetec and was told to use Semi Synthetic, i wanted to use the fully synthetic oil but was told not to

oilman

Myth.

Just use the correct viscosity synthetic.

The Myths regarding Synthetic Oils
The benefits of Synthetic motor oils have been much debated over the last 10 years and misinformation is rife, particularly on the internet.
There are many so-called experts out there who should know better but hopefully this post will shed some light on some of the most common myths.

What are Synthetic Oils?
Synthetic Oils are fuel efficient, more fluid and resistant to thermal breakdown, they are constructed in laboratories using basestocks and special additive packages. They are specially formulated to meet and perform to standards set by API and ACEA as required by OEM’s.

Synthetic motor oils damage seals.
This is untrue. Why would lubricant manufacturers build products that are
incompatible with seals. The composition of seals present problems that all types of oils must overcome.
At the end of the day, it is the additive pack in the oil that counts. Additives are added control the swelling, shrinking and hardening of seals.

Synthetics are too thin.
This is untrue. In order for an oil to be classified in any SAE grade (0W-40, 5w-40,10W-40 etc) it has to meet guidelines with regard to viscosity or thickness.

For example, any oil with a viscosity of 10W-40 has to operate at -25 degrees centigrade and 100 degrees centigrade to pass these tests or it cannot be rated as a 10W-40.

Synthetics mean higher oil usage.
This is untrue. Synthetic motor oils are intended for use in mechanically sound engines, that don't leak oil. In these engines oil consumption will actually be lower because of the lower volatility of Synthetics. They also have better sealing capabilities between piston rings and cylinder walls. Synthetics also have better oxidation stability. (They resist reacting with oxygen at high temperatures)

Synthetic Oils are not compatible with other oils.
This is untrue. The synthesized hydrocarbons, polyalphaolefins, diesters and other materials from high quality basestocks are fully compatible with other oils.
It is best to stick to the same oil for topping up that you have in the engine. It is best not to mix oils, as additives are blended for specific oils. When different oils are mixed additive pack balances can be upset so for the best performance, it’s better not to mix them.

Synthetic Oils produce sludge.
This is untrue. It is a fact that they are more sludge resistant than other oils as they are better at resisting high temperatures and oxidation. Because Synthetic oils have higher flash points, they withstand evaporation better leaving less deposits.

Synthetic oils can't be used with catalytic converters.
This is untrue. There is no difference between synthetic and other oils with regards to the components. Neither will damage catalytic converters.

Synthetic oils can void warranties.
This is untrue. No major manufacturers specifically ban the use of synthetic
oils. More and more new performance cars are factory filled with Synthetic oils.
Vehicle warranties are based upon the use of oils meeting specific API Service
Classifications and recommended viscosities.

Synthetic oils will last forever.
This is untrue. There are some people that believe that synthetic basestocks themselves can be used forever. However, it is a well known fact that eventually the additives will break down and cause the oil to degrade. The additives in the oil are effectively “used up” by moisture, fuel dilution and acids. Regularly topping up the oil will help but sensible oil change periods are recommended.
Synthetic oils will protect an engine for far longer periods than non-synthetics.

Synthetic oils are too expensive.
This is untrue. It has been proven through testing that Synthetic oils do have longer drain periods and provide better fuel economy. Add this to reduced engine wear and better reliability then do the maths. They are in reality better value for money than other oils.

Cheers
Simon

oilman

That's just rubbish, a 5w-30 semi is exactly the same viscosity as a 5w-30 fully synthetic.

Cheers
Simon

PS. Both semi and fully synthetics carry Ford Approvals, check my website and you'll see all different ones.

Zetec Andy

cheers for the reply, although i did order i good oil from my local motor factors a bottle of Comma semi synthetic turned up and i had already got the car on the ramp and dropped the oil, so i had to use it

st3v3

oilman
you say on scoobynet "But, if you drive a high performance car, and you intend to keep it for several years, and maybe do the odd “track day”, then you need a genuine Ester/PAO (Poly Alpha Olefin) synthetic oil. "


can you tell us which oils these might be please,just to make it easier for us to find on the shelf?

James

Cool, thanks for that i'll go and use some fully synthetic then, or am i better off with megnetec?

I had always understood you couldn't mix the two sorts of oil either, although i suspect the person who told me this also told me you couldn't use semi/fully in a engine with cork gaskets.

p.s.. just realised your're from cornwall! - hello fellow cornish man!

Also looking on your site.. Castrol RS 0W/30 what does that actually mean? - I know what it means as such but what does the 0 signify? - it isn't thicker than it should be when cold as it's a 0W rating? - therefore it'll spend less time getting to the correct working viscosity?

frog

Simon, Interesting post as usual from the oilman posse, but there are a few words I can't understand

This sums it up for me though

frog

also just noticed this...

No good for Fords then

boXXer

Very good question. Also, are you going to be @ ford fair? as i need some more silkolene pro-r 15-50.


also, i dont understand the ratings either, and what the 2 mean. would be very useful to find out from you.

boXXer

lol, same as. mine seems to lose a bit. EEEK!

oilman

Yes we do have a stand at Ford Fair, my brother Guy will be looking after it, I'm at Rallyday next week.

We'll have plenty of the excellent Silkolene PRO S and PRO R there on the day.

This is a proper pao/ester synthetic

Cheers
Simon

boXXer

whats the difference between the S and the R? also, do we still get the PF discount if i mention it? he he.

boXXer

also, just looked at your site and whats better between the Motul 300v 15-50, and the pro r 15-50? as they are both ester based. cheers

James

Simon,

oilman

Ok, you asked for it

Now it's getting complicated

Let's start with the API basestock catagories, Group IV and V are the best ones, see below:

Basestock categories and descriptions

All oils are comprised of basestocks and additives. Basestocks make up the majority of the finished product and represent between 75-95%.

Not all basestocks are derived from petroleum, in fact the better quality ones are synthetics made in laboratories by chemists specifically designed for the application for which they are intended.

Basestocks are classified in 5 Groups as follows:

Group I

These are derived from petroleum and are the least refined. These are used in a small amount of automotive oils where the applications are not demanding.

Group II

These are derived from petroleum and are mainly used in mineral automotive oils. Their performance is acceptable with regards to wear, thermal stability and oxidation stability but not so good at lower temperatures.

Group III

These are derived from petroleum but are the most refined of the mineral oil basestocks. They are not chemically engineered like synthetics but offer the highest level of performance of all the petroleum basestocks. They are also known as “hydrocracked” or “molecularly modified” basestocks.
They are usually labelled/marketed as synthetic or semi-synthetic oils and make up a very high percentage of the oils retailed today.

Group IV

These are polyalphaolefins known as PAO and are chemically manufactured rather than being dug out of the ground. These basestocks have excellent stability in both hot and cold temperatures and give superior protection due to their uniform molecules.

Group V

These special basestocks are also chemically engineered but are not PAO.
The main types used in automotive oils are diesters and polyolesters. Like the group IV basestocks they have uniform molecules and give superior performance and protection over petroleum basestocks. These special stocks are used in all aviation engines due to their stability and durability. Esters are also polar (electro statically attracted to metal surfaces) which has great benefits. They are usually blended with Group IV stocks rather than being used exclusively.

It is common practice for oil companies to blend different basestocks to achieve a certain specification, performance or cost. The blending of group IV and V produces lubricants with the best overall performance which cannot be matched by any of the petroleum basestock groups.

This is the problem, too much meedling and cheapening by blending so the only way to tell is via chemical analysis to determine the trace against proven products.

So, ALL 0w oils are synthetic, commonly PAO

ALL 5w oils contain an element of the good stuff but the % depends on the cost of the oil generally.

10w, 15w and 20w can be blended using cheap mineral basestock and therefore most are not proper synthetics.

There are a few exceptions that we know of, the list is not exclusive but it's based on data that we have seen.

Mobil1 PAO
Silkolene PRO S and PRO R PAO/Ester
Fuchs Titan Supersyn PAO
Motul 300V PAO/Ester
Motul 8100 PAO mainly althouth the 0w-40 contains ester
Redline PAO/Ester
Amsoil PAO
Castrol RS 0w-40 PAO

Where can you get these oils? Guess

Mobil1, Silkolene, Fuchs, Castrol and Motul from me

To your door overnight

Or catch us at Ford Fair to save carriage

Oh, we'll be at Rallyday and Trax too

Hope this helps

Cheers
Simon

oilman

Pro S comes in 5w-40 and 10w-50

Pro R comes in only 15w-50

Same formulations just labelling!

I'm sure he'll be nice to you if you mention Passionford.

Afterall, you're not a bad bunch

Cheers
Simon

oilman

They are both great oils with similar chemical traces.

For us the Silkolene has the edge and it comes in 5L containers and is slightly cheaper by the litre. It's also red!

They are both better than M1 for the same money, I would have no problem recommending either, top oils!

Cheers
Simon

oilman

This is what the numbers mean.

The "w" number is the cold crank viscosity and the lower this is the quicker the oil will flow when you turn the key. 90% of wear occurs here so the lower the better.

The second number is the sae number and this indicates the high temperature protection or heat resistance. Sae 50 is thicker then sae 40.

So, look for an oil that protects well on cold start and also when hot.

Take a base oil like 10w-40 and compare it to others:

5w-40 has better cold start protection and the same hot performance

10w-50 has the same cold start protection and higher hot performance

15w-50 has poorer cold start protection and the same hot performance

Get the idea? If not, catch up with my brother Guy at Ford Fair and he'll be happy to give you a lesson

Cheers
Simon

Rob Virgo

iTrader: (6)

oilman,

cheers for the info ,
always found the mobil1 or rs 0w oils made the car a lot tappetier and seems to run through the engine but the 10w stuff it ran quieter and lasted in engine.
have seen this in a few cossie engines,am i imagining it or is it backed up by fact.

rob

oilman

In would have said 5w-40 is a good choice personally.

Cheers
Simon

James

very interesting, what oil would you recomend for my kent crossflow engine bearing in mind it's just been re-built?

oilman

Once run in, use a good quality 5w-40 synthetic.

Cheers
Simon

space hoppers

hi simon its james just to say thanks for putting my car on the display at ford fair and thanks for the oil i shall be putting it in next oil change. had a lot of good comments from people so all the work on car was worth it. met dan from turbo technics who had helped me with my turbo and was very helpfull.i shall be at rally supercar day also so will come and say hello thanks again and if you need my car again at all just give me a ring cheers james

Joris_FRST

What would you use in a CVH engine ?

Ford Fiesta RS Turbo.

I currently use Castrol RS 10 W 60. (i understand this is not a true synthetic) car is fine with it though.

oilman

Joris FRST.

What year is the car?

Cheers
Simon

Joris_FRST

Hi,

car is 1991 built ford fiesta rs turbo.
Engine is ford recon engine, about 30k miles.

oilman

The oil you should be running is 5w-40.

I would suggest that you stick to this recommended grade as the car runs 14cst at 100degC, the sae 60 is 24cst at 100degC which is 70% thicker than needed.

This leads to lower mpg, bhp at the wheels and additional friction, heat and engine wear in the long term.

Cheers
Simon

DaveEscos

Mr Oil Man,
can you please reccomend suitable oils for the following on an Escort Cosworth

Quaife big tooth gearbox
Transfer box
Front ATB diff
Power steering fluid


and can you supply all 4 ?


cheers

Dave

FASTdan

oilman, as always a very informative post. a quick question for you....

In an engine such as a Fiesta RST (low mileage rebuild) running castrol magnatec 10-40 currently (but may change to what you recommend) what sort of pressure drop do you expect as a result of increased temps? ie standard CVH pressure specs @ 80degs C are:

14psi @ 900rpm
41psi @ 2000rpm
63psi peak

my car tends to run around 90degs but i only see 35psi, and a peak of just under 50. idle is always fine at 14-16psi. these are taken on a reasonable quality capillary mocal oil pressure/temperature gauge.

I am trying to decide if i have anything to worry about or if it is simply a degradation due to temp.

cheeers

oilman

Dave,

Quaiffe actually recommend the Silkolene SYN 5 75w-90 for their boxes.
This can also be used in transfer and front diff.

I have all the products you need, just email me for a price list.

sales@opieoils.co.uk

Cheers
Simon

oilman

If you switched to something like Silkolene PRO S 5w-40 I would not expect any change in oil pressure to a 10w-40 as they are both sae 40's but the difference would be that the Silkolene would maintain these pressures for a much longer period of time being a proper synthetic.

You would get more pressure from an sae 50 but depending on quality the time period for this pressure would vary.

Cheers
Simon