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SE NC. Not near as bad as FL or TX but still sweltering sometimes Jul-Sep. My 9000 is not a turbo, though so I'm not too concerned with bay temps.
 

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Georgia /Florida high heat high humidity? I would go Pentosin….way cheaper than replacing a ps pump due to heat issues. I tested and developed cars for decades in AZ,GA,FLA, Alabama and Texas....viscometrics trump cheap anyday. And heat is an issue, SAABS have silly elevated under hood temperatures compared to N/A autos.
Then you should know -- the difference between Pentosin and DexIII is minimal -- except the cost.
285k miles on my 9K with original p/s pump and the cheapest dexIII I can find...
 

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Then you should know -- the difference between Pentosin and DexIII is minimal -- except the cost.
285k miles on my 9K with original p/s pump and the cheapest dexIII I can find...
The visco index is still half that of Pentosin. However the thickness at 40C of Pentosin is double that of Dexron III and equal at 100C. So, I would say that Dexron III would flow better than Pentosin except under extremely cold conditions (sub-freezing).
 

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The kinetic visco of Pentosin at 40C is 19 sqmm per sec. Dexron III is 34. With PS being hydraulic I would say that Dexron III is thinner and would pass through valves faster unless the temps are sub freezing where Pentosin beats them all with a high visco index over 300.
 

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That said, thicker PS fluid may work better in old systems that have stiff seals so Pentosin may likely work better all around in these older cars, for a wide temp range. So many factors involved that you can not just look at a few specs and say X is always better than Y for every case.
 

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Been years since I looked the two up on MSDS and viscosity charts -- I don't recall seeing any practical difference between the two. That's why I used the dexIII.
The biggest difference I can recall being the dexII could handle more heat before breakdown...

Biggest concern with choosing different oils is the base oils compatibility with the seals used in the system. In this case there is no compatibility problem.
 
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