I'm posting this as it's of general interest to all here.

What's more, it's fact not fiction so please take time to read it.

Due to the court case in the states between Mobil and Castrol, you may not always be getting what you think you are so be careful, hydrocracked oils are not synthetics in the true sense of the word as they are molecularly converted petroleum oils, synthetics are not, they are built by chemists in laboratories "brick by brick" and are far superior.

Unfortunately, apart from in Germany, a manufacturer can label the inferior "hydrocracked" oils as synthetics and therefore the only true way of working out the quality is price although even this is not certain as there are some very expensive "hydrocracked" oils out there which are sold on their brand name, Castrol is a good example as they were the Company that Mobil took to court over the labelling issues.

Here is some more reading for those interested:

“HYDROCRACKED” (HC) or MOLECULARLY CONVERTED (MC) BASESTOCKS

There are many petroleum oils available on the market that are so pure and refined, they can now be passed off as synthetics.
They are not made from true synthetic basestocks (at least not in the way that synthetics have traditionally been defined), but they have so little in common with traditional petroleum basestocks, it is really somewhat silly to classify them as petroleum oils.
Petroleum oil basestocks can be put through a super-extreme refining process called “hydrocracking”. In some cases, as in the case of one particular name-brand "synthetic" oil, these highly refined petroleum basestocks can actually be termed and sold as "synthetic".
It is completely legal for lubricants manufacturers to label these oils as "synthetic".

These are extremely high performance petroleum basestocks, but they are not truly synthetic the way that most people understand the term and will not necessarily perform to the same level as a premium synthetic oil like PAO (poly alfa olefins) or Esters.

Hydrocracking involves changing the actual structure of many of the oil basestock molecules by breaking and fragmenting different molecular structures into far more stable ones. This results in a basestock which has far better thermal and oxidative stability as well as a better ability to maintain proper viscosity through a wide temperature range - when compared to a typical petroleum basestock.

Although contaminants are still present, and these are still petroleum basestocks, contamination is minimal and performance characteristics are high. This process also can turn a wider range of crude oil stock into well-performing petroleum lubricant basestocks.

TYPES OF SYNTHETIC BASESTOCKS

Synthetic basestocks are not all the same. There are few different chemical types that may be used as synthetic basestock fluids. There are only three that are seen commonly in automotive applications:

Polyalphaolefins (PAO's)
These are the most common synthetic basestocks used in the US and in Europe. In fact, many synthetics on the market use PAO basestocks exclusively. PAO's are also called synthesized hydrocarbons and contain absolutely no wax, metals, sulfur or phosphorous. Viscosity indexes for nearly all PAO's are around 150, and they have extremely low pour points (normally below –40 degrees F).
Although PAO's are also very thermally stable, there are a couple of drawbacks to using PAO basestocks. One drawback to using PAO's is that they are not as oxidatively stable as other synthetics. But, when properly additized, oxidative stability can be achieved.

Diesters
These synthetic basestocks offer many of the same benefits of PAO's but are more varied in structure. Therefore, their performance characteristics vary more than PAO's do. Nevertheless, if chosen carefully, diesters generally provide better pour points than PAO's
(about -60 to -80 degrees F) and are a little more oxidatively stable when properly additized.
Diesters also have very good inherent solvency characteristics which means that not only do they burn cleanly, they also clean out deposits left behind by other lubricants - even without the aid of detergency additives.
They do have one extra benefit though, they are surface-active (electrostatically attracted to metal surfaces), PAO’s are not “polar”, they are “inert”.

Polyolesters
Similar to diesters, but slightly more complex. Greater range of pour points and viscosity indexes than diesters, but some polyolester basestocks will outperform diesters with pour points as low as -90 degrees F and viscosity indexes as high as 160 (without VI additive improvers). They are also “polar”.

Other synthetic basestocks exist but are not nearly as widely used as those above - especially in automotive type applications. Most synthetics on the market will use a single PAO basestock combined with an adequate additive package to provide a medium quality synthetic lubricant. However, PAO basestocks are not all the same. Their final lubricating characteristics depend on the chemical reactions used to create them.

Premium quality synthetics will blend more than one "species" of PAO and/or will blend these PAO basestocks with a certain amount of diester or polyolester in order to create a basestock which combines all of the relative benefits of these different basestocks.

This requires a great deal of experience and expertise. As a result, such basestock blending is rare within the synthetic lubricants industry and only done by very experienced companies. In addition, although such blending creates extremely high quality synthetic oils, they don't come cheap. You get what you pay for!

Cheers
Guy

 

I read the top bit but to sum up, would you suggest not using castrol rs then??? What oil would you suggest for a cossie?? Mobile motorsport??

 

Read the rest while you are waiting interesting read

 

sod that. My eyes are hurting from reading the first paragraph

 

yeah, but you're misssing the point about WHY you might choose one oil over another.. rather than follow the sheep and say 'X' is crap and 'Y' is the best thing since.... because... well i don't really know why...
seriously, it's worth the read

 

10w-40, 10w-50, 15w-50. You could go for Mobil 1, Fuchs, Silkolene try to steer clear of the 10w-60, despite popular belief it is just too thick.

Now read on as I will be asking quetions later!

Cheers

 

thanks oil man. I will read it

 

fuchs and silkolene are one and the same arent they?

 

Still gone a bit over my head! lol

Intresting reading but how do u know what u get does it say on oil tins etc?

 

i knew about this a while back - which is why i would not touch casrtrol RS 10 60 with a 10 foot pole

 

Quite right, FUCHS own Silkolene.

Silkolene Provide the higher spec oils though.

Cheers

 

Had a very interesting chat about this with a guy from the Q8 oil company not so long ago He opened our eyes to all the going's on - and if you understood it all it was very interesting

 

The fact that SOOOOOoooo many people do use it and never have problems with it even in big BHP engines makes me think it'll be fine in my lowly ~250bhp pulsar.

 

I think this is an important point - oilman, put us right if not pls - it is wrong to say that Castrol RS is crap, it isn't IMO, as proven by the many that use it in pretty adverse circumstances, BUT there is better quality out there... it's only 'better' though if you actually need 'better' for the application and get benefit from it.

The most important thing is to be making an informed choice for your own individual case, after understanding the facts. There is so much bollox spouted by so many people who actually know nothing, and choices are being made on folklore and pubtalk alone..

 

Personally, I would use Silkolene PRO S 10w-50, its PAO/Ester but this is my favorite oil on paper.

Cheers
Simon

 

well i dont need to read it all cause i wont disgrace my engine with synthetic shite oils anyway

 

I never said it was crap, in fact I sell it. But if you want to put the best quality oil in to afford the best protection then look at a PAO/Ester like Mobil or Silkolene.

You've read the reasons why they are better but it's a question of whether you wish to use an average oil and change it regularly of put something better in for peace of mind.

Cheers
Simon

 

nooo nooo Simon, I wasn't for a moment suggesting you were!
but i was pre-emting the inevitable onslaught coming along later..

This is exactly what I mean.. as you say, you sell a wide range, and there is a choice to be made, it's good to have some decent information to back up the choices.

indeed your posts here and on RSOC have made me think a bit more about the reasons for using one or another..

 

Castrol rs IS pants

everyone knows that, it even comes out like water

mobil 15-50 all the way

 

I agree, i tried castrol RS once and that was enough, never again, it made my car tick like a bitch. Although i was told the other day by a stranger that Mobil 1 has been known to cause cossies to put rods through the block.

Doe's anyone know if this is true?, coz I think it's b*ll*x myself.

 

A great Read Simon, ive learnt a few things from that, many thanks for taking the time to post it. Deffo one for the essay forum this

Absolute horseshit!!!
Where does this bollox come from?

 

here we go.. so,... so far Castrol RS is no good, nor is Mobil 1..... so which one next?

out of curiosity, which viscosity ratings are we dealing with in each case? what was the oil pressure in each case? What engine? what condition?.....

 

Stu,

I think it comes from a case/cases where an owner may overfill their Cossie with oil - as in 20-25mm (or more) over the MAX mark, then drive the car on the motorway/or highish revs.........

Then again, I could be wrong

 

we(BP) stopped using a hydro cracker in the early 80's(when we were owned by mobil) due to it being an outdated system and not being able to crack off at the levels/quality we needed to and invested millions in a cat cracker!!!
fuchs by there base stocks from BP !!!(who own castrol)


this is the biggest load of crap i have ever heard and i have heard some!!!

sorry if i offend the author of this thread....but don't believe the hype dude!!

Pugo

 

oilman - how come you sign guy at top then simon later.

you stink of MYCROFT at first reading? but i have put no time into this and dont wish to offend.

Martin

 

what about mineral oil? it better? markk mentions it...

valvoline racing is semi-synth i think, and 5/55 or somthing, cheap too...

 

Over here the Mobil1 (motorsport/racing) is only sold as motorcycle oil. Is it exactly the same oil? I guess it is as its for 4-stroke motorcycles but if not it would be nice to know.

 

What is it that is a load of crap Pugo?

 

i ordered some Silkolene Pro S off Oilman. it came the next day too

prices aren't bad either, paid Ł60 ish for 2 5L bottles inc next day delivery - i couldn't find this oil anywhere in the local area.

 

Motorcycle oil will have different shear properties as motorcycles have wet clutches AFAIK

Don't know how this would affect it's performance in a car engine tho

 

it's all a big consipracy lol

dont u think it strange how castrol dropped the 10-60 - which seems like a perfect viscostity

 

they did?? when did this occur?

 

Castrol have dropped 10-60 ? News to me.

 

They dropped it as a mainstream oil, and replaced it with 0-40. It's only available through specialists

 

All my local Wilco's stock it. I'd hardly call them a specialist.

 

ah cool, so haven't dropped it then.. that's why you can still buy it
Mobil1 did exactly the same , but they did it first.. Castrol followed suit IIRC.
Marketing..

 

Motor factors always say 'They've stopped making it mate' when they only stock the 0-40

 

Like i say - it isnt mainstream anymore

 

no stranger than Mobil one dropping the proper stuff in favour of 'mainstream' 0w40 though???? Then call it 'Motorsport' and sell it from specialist outlets..
Halfords for example chose to stock RS0W40 as their 'mainstream' version, then told everyone that 10W60 was no longer available .. or is that the conspiracy?? :d

 

00-40 is like piss water, never had any problems with Castrol RS 10-60 myself or thr thousands of litres ive sold

Matt