Brookfield Vis @-40/Castrol Mercon V vs. Valvoline Mercon V

[The Critic]

Actually two questions in one thread.

1) Is using the Brookfield Viscosity at -40 a possible method of guessing the quality of the basestocks used? If the Brookfield viscosity at -40 is lower with one product compared to another, does this mean that the product is using higher quality basestocks for better low-temp performance? Or are they simply using pour-point depressants?

For example, Pennzoil Multi-Vehicle ATF, which someone told me was a GrpIII basestock, has a Brookfield Vis between 8-9000 at -40. Valvoline Mercon V and Castrol Mercon V, have brookfield viscosities of 12K and 13K, respectively, compared to Valvoline Maxlife ATF which tests out at about 17-18K.

2) Which is better, Valvoline Mercon V or Castrol Mercon V. Valvoline is $3.59/qt, while Castrol is $2.89 (?) per quart. Aamco Mercon V Blend isn't avaliable at the AutoZones in this 'hood so its out of the question, only Castrol is.

Putting price aside for a moment, my main concern with the Valvoline product is its advertisement as a Multi-Vehicle ATF. In addition to being licensed for DexIII(H) and Mercon V apps, it is also suitable for use in ATF+4, Honda ATF Z-1, SP-III, Toyota T-IV, etc applications. If so, doesn't this mean that the fluid contains an additional range of friction modifiers for the fluid to be suitable for use in those other apps?

Would all of these "other" friction modifiers have a negative effect on shift performance if I'm only using the fluid for a Mercon V app? I ask this as Castrol Mercon V is only certified for Mercon V apps and NO other apps.

Thanks.

 

[unDummy]

I'm guessing that basestock and additives used can affect the -40 visc, so I wouldn't use that single spec to compare fluids.

Concerning Mercon-V, I've use Pennzoil Multivehicle and would say its one of the best MV's out there. I dislike the Castrol and stock ATF(Mazda MV). The Motorcraft was not any better then the Aamco or Valvoline, which are good choices too.

Use the Pennzoil or Valvoline MV over Castrol if thats what you have to choose from.

I was also under the impression that the required spec for Merc-V is 12000 at -40. Castrol Merc-V doesn't meet the spec. Valvoline Maxlife doesn't either.

I wouldn't worry about 'friction modifiers'. IMO, to keep it simple, they're the same with <> limits. Most fluids spec a 'range' of FM and is why a fluid can meet multiple MFG specs.
The longer life additives is one thing that I worry about. But, I ignore that fear by practicing regular ATF maintenance. IMO, fresh multivehicle fluid is better then overused higher mileage OEM eternal life fluid.

 

[MolaKule]

quote:

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Is using the Brookfield Viscosity at -40 a possible method of guessing the quality of the basestocks used? If the Brookfield viscosity at -40 is lower with one product compared to another, does this mean that the product is using higher quality basestocks for better low-temp performance? Or are they simply using pour-point depressants?

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No, because one could still use a lower group basestock of lower viscosity to achieve the stated Brookfield viscosity.

Reread the "Question of the Day" topics (in Science and Technology of Lubricants and Oil additives) such as:

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=21;t=000024

PPD's can help here even when using lower group fluids such as GroupI.