HT/HS question

[SEC]

GC 0W30, or Castrol SLX as it is badged in the UK, is available here as SLX or SLX II. The SLX II is said to be formulated for VW/Audi longlife requirements. I noticed on a previous thread, which I did not bookmark, a comment that SLX II is not suitable for engines other than VW Audi due to low HT/HS. Could someone explain what this means, please? If this is so, why does the packaging not indicate that it is not suitable for other vehicles? Shell does a similar product - 0W30 meeting VW/Audi requirements. I have been unable to find the specification for this oil as yet - would the same thing (unsuitable for other vehicles) apply to this oil?

Thanks
SEC

 

[mountravlr]

It is difficult to advise, with regard to the little information supplied by the labels on the containers. HT/HS are specifications regarding High Temperature and High Shear, and these vary considerably among synthetic and fossil based oils. The HT/HS of the synthetic oil in my vehicle according to ASTM D4683 is 3.5 for a 0W-30 which is a moderate value compared to heavier viscosity oil.

 

[ekpolk]

I'm experimenting with GC for the first time myself. I asked about its HT/HS here, and another member indicated that it's rating is 3.5, which compared to other oils in this range of viscosities seemed pretty good. There's a spreadsheet on another site (can't find my bookmark either...) that includes the HT/HS for a lot of oils, and most of the 5w-30s and 0w-30s seem to hover between 2.8 and 3.0, but as I recall, GC was not differentiated from the other version of Syntec. Anyway, I'd love to find that "low HT/HS for GC" info so I could compare with other info.

 

[JohnBrowning]

Lets assume a few things first since they were omitted. First you are not towing in exteme heat. Second you are not raceing you car in a rally type event. Third your engine is in sound working order. If we assume the above then the general rule of thumb is that the oil must have an HT/HS above 2.6 for long valve train life. I personel like an oil to be at least at an HT/HS os 2.9 or higher. Mobil-1 M1R OW30 Race formula just barley meets this so it is being included in the list of oils I am trying. It also has alot more antiwear additives then the rest of M1's line up. I have to say that I am rather partial to Delvac-1 and their New SUV formula. I think that 5W40 is the ultimate comprimise for yuear round use! I have not recently tried Delvac1 or SUV but have tried other 5W40 products and was more then happy with them.

Generaly it has been my experince that an HT/HS of at least 3.5 or higher is preferred for sustained high speed driveing or heavy towing.

 

[haley10]

Typical with the Euro cars. I think all they are trying to say is they are recommending a 5W-40. The Castrol or even M1 0W-40 wouldn't be thick enough. They are wanting a mid-range 40wt for viscosity.

 

[Patman]

GC's HTHS is actually 3.6 according to the specs I got from Castrol Germany last year.

 

[TC]

Stolen from another website: "The High Temperature/High Shear Test measures a lubricant's viscosity under severe high temperature and shear conditions that resemble highly-loaded journal bearings in fired internal combustion engines. In order to prevent bearing wear, it is important for a lubricant to maintain its protective viscosity under severe operating conditions."

For what it's worth, here's a few HTHS numbers from spec sheets for USA oils (higher numbers are better):

Union 76 5w-30/10w-30: 3.1
Union 76 10w-40: 3.8
Pennzoil Multigrade 5w-30: 3.1
Pennzoil Multigrade 10w-30: 3.2
Pennzoil Multigrade 10w-40: 3.7
Citgo Supergard 5w-30: 3.2
Citgo Supergard 10w-30: 3.0
Citgo Supergard 10w-40: 3.6
Citgo Supergard 20w-50: 4.6
Pennzoil Long Life (gas/diesel) 10w-30: 3.5
Pennzoil Long Life (gas/diesel) 15w-40: 4.3
Kendall GT-1 5w-30: 3.0
Kendall GT-1 10w-30: 3.1
Kendall GT-1 10w-40: 3.6
Kendall GT-1 20w-50: 4.3
Kendall GT-1 Synthetic 5w-30: 3.1
Kendall GT-1 Synthetic 10w-30: 3.2
Kendall GT-1 Synthetic 5w-40: 3.8

Syn's are superior, as would be expected, but check out "diesel" kickin' buttock!

[ May 16, 2004, 12:52 AM: Message edited by: TC ]

 

[Primus]

Without knowing the car nobody here can give you some recommendations which one to use: SLX or SLX Longlife II. It may happen that both would be OK.

Castrol SLX Longlife II 0W-30 properties slightly vary depending on the country of origin:

Density, 15 C ...... 0.843-844
Viscosity, 40 C .... 54.7-55 cSt
Viscosity, 100 C ... 9.9-10.1 cSt
Cranking, -30 C .... 3200 cP
Viscosity index ..... 171-174
Pour Point ........... - 51 C
TBN,KOH ............. 10.2-11.3

As for HT/HS, unfortunately Castrol does not indicate HT/HS for this oil, but according to VW 503.00/ 506.00/506.01 specs it should be between 2.9 and 3.4. Similar type of special oil for BMW: Castrol SLX LL01 FE 0W-30 has HT/HS = 3.0, but for Audi/VW it may be higher. In respect of HT/HS requirements the most interesting of SLX range is Castrol SLX Formula GM 0W-30 that meets both specs, GM LL A-025 and B-025. Think it’s the only reason why its HT/HS is 3.5.