Castrol TWS 10w-60 - - why API SJ?

[m6pwr]

I’ve posted a VOA and UOA (see separate threads) for a sample of Castrol TWS 10w-60, API SJ oil as used in a ’05 BMW M3. These are my first readings on this type oil,
and, considering the application, was surprised to find such relatively low levels of phosphorous/zinc anti-wear additive (641/796 in the VOA), although there is a good amount of boron which I believe is also an anti-wear additive.

I have one question: The oil is rated API SJ. What is the advantage or possible reason for formulating this oil to such an old API rating?

 

[Doug Hillary]

Hi,
m6pwr - You said this:
"What is the advantage or possible reason for formulating this oil to such an old API rating?"

This lubricant has a very long history and SJ was a great formulation - it is still current - however you may have old stock..........? It will be A3/B3/B4 compliant

It was one of the first lubricants to use quite low phosphorus levels (prior to 1998) along with GC 0W-30 Formula SLX

Without going into details it has a very advanced AW package!

 

[m6pwr]

Doug -

Thanks for the info.
Glad to hear that this oil has good AW performance. The oil in the UOA was probably manufactured sometime in '07.

 

[Doug Hillary]

Hi,
m6pwr - Sorry for my curt response earlier but I have covered my relationship to this lubricant numerous times before. I have been involved with it since around 1978-9

 

[jaj]

Originally Posted By: m6pwr
I have one question: The oil is rated API SJ. What is the advantage or possible reason for formulating this oil to such an old API rating?


When the oil was originally formulated in the 90's as Castrol RS Racing Syntec 10w-60, API SJ was current. Newer formulations don't "work" as well as this one did, so BMW kept it alive by having Castrol private label it for them as TWS. More recently, Castrol re-released it as Edge 10w-60.

The label only shows API SJ/CF and the viscosity. No mention of ACEA.

 

[d00df00d]

Originally Posted By: jaj

The label only shows API SJ/CF and the viscosity. No mention of ACEA.

Ah, the beauty of an application specific oil. No need for the formulator to pay for more than one or two approvals...

 

[Doug Hillary]

Hi,
carrying on from jaj's comments the lubricant started off in 1978 as "Castrol Formula R Synthetic" of 15W-50 viscosity and rated as API "SE". It was Castor based then, red in colour and with the lovely exhaust odour that Castrol "R" users know about!

Sauber-Mercedes (turbo V8) used it to win the 1989 & 1990 WSC Championship and the 1989 Le Mans. It handles fuel dilution very well! It was used extensively in HB Cosworth F1 engines and by Porsche and BMW as a race lubricant too. It was also used in ZF's (and other) racing gearboxes

 

[JAG]

Doug,
Why would a high-dollar racing team put motor oil in a gearbox rather than a gear oil? I would expect a gear oil to have better extreme pressure (EP) performance than a motor oil which does anti-wear duties but not EP so much. Oh, in afterthought if it contained castor oil, that may help in a gear box, but still, I'd think a gear-specific oil would be best. Thanks.

 

[d00df00d]

Low tooth loads in those gearboxes, perhaps?

 

[Doug Hillary]

Hi,
JAG - Depending on the design of the gearbox as you know, fluids used can range from ATF (MB from the 1950s>) via engine lubricants to a GL5 EP fortified gear lubricant

A typical case is the many Brands of heavy truck gearboxes around. One in particular (Eaton-Fuller Roadranger - constant mesh) always called for a SAE50 engine lubricant (or a SAE 90 GL1 spec). Many Fleet people would say "...too thin..." and use a SAE90 GL5 gear oil instead! The problems with this were many including cold selection issues, galling and metal removal and a greatly reduced service life. A synthetic SAE50 lubricant extended seal and component life by four times and more - gear wear became almost zero up to 2mkms and more (depending on use/Driver skills)

Many gear boxes require a zero EP formulation and their design (such as constant mesh/double or triple countershafts) enables very low tooth loading. Adequate cooling is paramount

German gearboxes - both cars and trucks - and their derivatives have long called for the "ATF type" of lower viscosity lubricant

Recently I was in the workshop of a V8 Supercar (500hp plus) team with a certain Oil Co sponsor (NOT Mobil) and some Castrol lubricant containers were there. When asked about this the Head Tech did not know the full details except that it was supplied by Castrol, type unbranded and that it works the very best of all! Perhaps it was 10W-60!

As usual it is a case of horses for courses

 

[JAG]

Thanks for the interesting education, Doug!

 

[jaj]

Originally Posted By: m6pwr

I have one question: What is the advantage or possible reason for formulating this oil to such an old API rating?


To expand on Doug's point, TWS is a remarkable product that performs at levels that most oils don't even attempt, and yet it's available over the counter at your local BMW dealer.

Most "dealer" oils get a lot of derision, but this is a case of a vastly superior product dressed up as a sleeper.

 

[330indy]

+1000

it is liquid gold. my '06 M Roadster just loves it!