GTL = higher PVC = a lot less wear says Chevron

[Gokhan]

Originally Posted By: donnyj08
I was under the assumption that there is no Group III+. Doesn't it jump straight from group III to Group IV?

Group III+, III++, etc. are simply improved Group III base stocks. The names are not official API designations but given by oil industry. GTL is yet a further improved Group III base stock, produced from natural gas rather than petroleum.

 

[donnyj08]

Originally Posted By: Gokhan
Originally Posted By: donnyj08
I was under the assumption that there is no Group III+. Doesn't it jump straight from group III to Group IV?

Group III+, III++, etc. are simply improved Group III base stocks. The names are not official API designations but given by oil industry. GTL is yet a further improved Group III base stock, produced from natural gas rather than petroleum.



I am well aware of GTL. I only asked because according to the Pennzoil Q&A under the Section GTL/Testing question #3 Pennzoil states that there is no such thing as group III+. GTL is classified as group III.

According to the numbers it produces it rivals group IV, however Group III+ is in fact not used to classify base stocks, At least According to Pennzoil.

BTW Thanks for posting this Thread, Gokhan. Very intereting!

 

[SR5]

Thanks Gokhan Thanks Shannow, very helpful comments.
Good questions DeepFriar.

 

[Shannow]

Gohkan, I've got to admit that I haven't given EHD much shrift when it comes to bearings, predominantly due to the materials in the bearings only having their own elastic limits in the 30MPa range...meaning that localised pressures in that region are likely to perform plastic deformation, and cyclic loadings close to that limit will cause work hardening, fatigue, and spalling.

Not saying that it's not there, just why I've considered it a low order player in the bearing metals.

Herzian stressed in rolling elements and cams and the like, never an argument from me.

 

[Gokhan]

I think it depends on the bearing, operating conditions, and viscosity used. As you said, nowadays OEMs are trying to put the bearings close to the EHL regime, in which the friction is the lowest on the Stribeck curve (lower than in the HL region), therefore resulting in big savings in fuel economy.

Regarding Group III+, again, it's not an official API group but it's a common term that is used in the oil industry. For example, ExxonMobil refers to their Visom base stocks, which are of a little lower quality than GTL, as Group III+ or GTL precursor:

ExxonMobil Visom Group III+ base stocks

ExxonMobil explains Mobil 1 SN formulation, base stocks, and other ingredients (PDF link)

 

[donnyj08]

Originally Posted By: Gokhan
I think it depends on the bearing, operating conditions, and viscosity used. As you said, nowadays OEMs are trying to put the bearings close to the EHL regime, in which the friction is the lowest on the Stribeck curve (lower than in the HL region), therefore resulting in big savings in fuel economy.

Regarding Group III+, again, it's not an official API group but it's a common term that is used in the oil industry. For example, ExxonMobil refers to their Visom base stocks, which are of a little lower quality than GTL, as Group III+ or GTL precursor:

ExxonMobil Visom Group III+ base stocks

ExxonMobil explains Mobil 1 SN formulation, base stocks, and other ingredients (PDF link)


Gotcha

 

[BrocLuno]

Originally Posted By: Shannow

Cool thanks for the background.

So it's more an EP/AW additive test than a "film strength" test as it's touted.

I have reasonably regular communication with an older cam guy, and he's adamant that reasonable design and installation would curb many of the issues.


Yeah, but racers and hot street guys are not into "reasonable" ... They're looking for maximum area under the lift curve which translates to steep ramps and rapid events which leads to valve train "bounce" and other side effects that increase loads dramatically ...

 

[RGR]

Originally Posted By: Gokhan

I am now considering the switch to the new generation of oil technology using GTL base stocks, currently available in Pennzoil Platinum PurePlus products.


Those of us who spent all that time collecting PU last spring are looking pretty well informed now aren't we! And considering we were paying $1/qt, we almost qualify as magical!!

 

[dailydriver]

Yes, today I even tried to get Summit Racing to start carrying the Pennzoil Platinum LX Euro 0W-30, since they ARE a Pennzoil dealer.

The sales rep put in the request, let's see IF the bosses/purchasing agents/bean counters approve it (They did NOT when I tried this for the Red Line 0W-40

).