Re: A JWS 3309 at AutoZone?- Castrol / 1 qt. Import Multi-Vehicle (Q-Ship)
If one drives about 15,000 miles/yr and averages 24 mpg and could save around $0.03/gallon on average that would be about $20. Now consider that your ATF is going to last 50-60,000 miles, about 4 years. That's $5/year increased maintenance cost in any given year.
Castrol Import M-V ATF
40°C, cSt ASTM D-445 36.6
100°C, cSt ASTM D-445 8.0
Viscosity Index ASTM D-2270 200
Brookfield [email protected]
-40 C, max,cP ASTM D-2983 13,000
Pour Point, °F (°C) ASTM D-97 -54 (-48)
Flash Point, COC, min °F (°C) ASTM D-92 406 (208)
Specific Gravity, 60°F ASTM D-1298 0.850
MOBIL ATF 3309
cSt @ 40ºC 35
cSt @ 100ºC 7.2
cP @ -40ºC (-40ºF) 14,000
Viscosity Index 180
Flash Point, ºC ›185
Pour Point, ºC ‹ -45
This is from the respective datasheets. I am going to assume that each one's additive package is sufficient to meet the jws 3309 lifetime stability spec--however, if swedespeeders are changing it out at much less than 80-100k miles, this may be irrelevant.
What I can see is that the Castrol product is higher viscosity ("thicker") at higher temps (operating temps) and thinner at lower temps than the Mobil product. The differences are not large, but significant, and may just reflect the nature of the basestock & additive package to produce the respective ATF. The Mobil product will flow a little more at normal operating temps and the Castrol will flow more at low T. The Castrol product has a higher VI which means that its viscosity changes less with temperature, but they are both in the same realm.
Will products perform the same? No, not measurably
so (as above), however, they could both be functional equivalents, i.e. both fit for purpose.
Assuming that Exxon/Mobil and BP/Castrol are two of the largest fuel & lube companies on the planet who get to hire pretty much any chemist or engineer that they want, I think that either product would be ok--and remember that Volvo uses Castrol lubes as its oe motor oil fill and recommends that we do the same.
I've met some Castol lube scientists, yes it was 15 years ago, and I would have to say that none of them were the kind of people that would knowingly sign off on a product that they knew was not to spec. We like to make a lot of ATF, motor oil, and fuel around here, but truth be told, I don't think we are talking about real step changes in technology with these products.
All that said, for $15-20 over 4 years, it's still a crap shoot.
And to further muddy the waters, it could be that Mobil 3309 meets all the same specs that the Castrol product does, but Mobil decided to call it 3309 instead of Multi-Vehicle--just to avoid the kind of debate that we are having here! Like many things today, the difference isn't science, but marketing!
Boiling it all down--maybe I should have said this first--you should not harm your tranny with the Castrol product, if it doesn't shift right (e.g. shudders) just change it out asap and live on.
No voodoo magic here.