Azrael

I don't understand now. You're trying to say that top of the line high ciscosity oil will degrade faster then middle shelf normal oil? We're not talking about petroleum ased mineral oil but top motorsport stuff here. I mean everybody here changes oile very often - so no need for longlife oils. You say 10W60 will perform like 10W40 after some time. But 10W60 will degrade faster, won't it? So which one will be better protection after lets say 1k miles 2k miles up to 5k miles? When usually people here change oil. And you forget about such factors as amount of oil in the engine which has some impact on it's lifetime.

Once again I'm only tring to understand you point better. Hope that isn't a problem.
It's quite important thing as you are speaking agains basically any tuner, motorsport service, performance car centre I know....

oilman

I am saying that a petroleum based 10w-60 will degrade faster than a 10w-40 or 10w-50 or 15w-50 synthetic oil.

It will start losing viscosity with use as opposed to a synthetic which will not over the same timespan 2-3000 miles.

All oils lose viscosity with use, it's the rate of that loss that makes the difference.

There is a test called HTHS to which all oils that have an API spec are subjected to which determines the shear stability of the oil.

This is what it's all about:

SAE has a test called HT/HS (High Temperature/High Shear) if an oil shears back too much on this high temperature test, it cannot be sold as a multi-grade oil. In fact, the test results from this test are very helpful in indicating the quality of the oil.

The higher the HT/HS number the better because this indicates less shearing. Petroleum oils tend to have low HT/HS numbers which barely meet the standards set by SAE.

Because petroleum oils are made with light weight basestocks to begin with, they tend to burn off easily in high temperature conditions which causes deposit formation and oil consumption.

As a result of excessive oil burning and susceptibility to shearing (as well as other factors) petroleum oils must be changed more frequently than synthetics.

Not all multi-viscosity oils shear back so easily. True synthetic oils (PAO’s and Esters) contain basically no waxy contamination to cause crystallization and oil thickening at cold temperatures. In addition, synthetic basestocks do not thin out very much as temperatures increase. So, pour point depressants are unnecessary and higher viscosity basestock fluids can be used which will still meet the "W" requirements for pumpability.

Hence, little or no VI improver additive would need to be used to meet the sae 30, 40 or 50 classification while still meeting 0W or 5W requirements.

The end result is that very little shearing occurs within true synthetic oils because they are not "propped up" with viscosity index improvers. There simply is no place to shear back to. In fact, this is easy to prove by just comparing synthetic and petroleum oils of the same grade.

Synthetics will generally have significantly higher HT/HS numbers. Of course, the obvious result is that your oil remains "in grade" for a much longer period of time for better engine protection and longer oil life.

Hope this explains.

Cheers
Simon

Glenn5

very informative what a read

Azrael

Simon, it doesn't explain anything :-/


We are not talking here about old - mineral vs. synthetic new.

We're talking about both very high quality SJ grade synthetic oils.


Let's stay with Castrol products which I know best. From what you say it seams that Castrol RS 0W40 is better then Castrol RS (or TWS) 10W60 for Cossie engine. I would like to know why.

As you said 0 or 10 doesn't matter in UK climate (in Polish neither - very rare to have more then -20).


Now let's compare them, I've got data from Castrol website in front of me:


RS 0W40:
-high temperature viscosity 13,2mm^2/s
SAE 0W40
API - SJ/CF


TWS Motorsport 10W60
-high temperature viscosity 24,0mm^2/s
SAE 10W60
API - SJ


Now. Why would the latter give less protection while driving at full power? I know about cold start wear and all that but Cossie engine has heat exchanger and oil quite quickly reaches operating temperature - what gives better protection then and why. COnsider we change it every couple thousand miles/kilometers.

oilman

Well, without saying too much here that could upset anyone.

The TWS is the better oil, formulated firstly for BMW's M series engines or at least 3 of them. TWS is not the same, it contains group IV/V basestocks giving it higher HTHS numbers. The RS 10w-60 (which incidently I sell) is a group III oil which is basically a hydrocracked or modified mineral oil, not a group IV (pao) or V (ester) synthetic.

If you'd like to drop me an email off the board I will explain further.

Cheers
Simon

Azrael

Oilman - you've got PM


I will continiue to use TWS on all my cars If I go competing I invest in Motul Le Mans

oilman

Azrael,

Hope you enjoyed the reading I sent you.

Opened your eyes I guess

Good luck with sourcing what you want

Cheers
Simon

Azrael

Thanks a lot mate

Just got too similar reading from Polish reserchers...

oilman

Hmmm, told you so rings a bell

Cheers
Simon

Azrael

I never argued what was in the reading. I always tryied to say that Castrol TWS 10W60 is one of the best oils for a Cossie

oilman

I know but many people believe that TWS and RS are the same thing.

They are not.

Cheers
Simon

Azrael

Yep, I've met opinion that TWS is "This new RS for BMW's". It's great oil though.

Dave Henshall

as above - i thought they were the same , just branded differently in different countries,

could you send me some bedtime reading aswel please simon davehenshall@msn.com

where can u get the castrol tws from then and how much...?

oilman

I can't unfortunately only RS. TWS is avialable in UK through BMW Dealers.

Email sent.

Cheers
Simon

Dave Henshall

Azrael

Schould (not 100% sure) be avalible through Toyota dealers. In Poland Subaru and Mitsubishi dealers who deal Castrol have it in stock usually.

oilman

We're not allowed to sell it (TWS) so that BMW Stealers can keep their nice little margins and the Customer is none the wiser.

Cheers
Simon

MATCOS

iTrader: (1)

good read that
cheers

Mat