Red Line Power Steering Fluid VOA

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AP9

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After just going through a little debacle with having to replace the power steering pump and lines in the Impala SS after the pulley shaft bearing completely destroyed itself, I decided to spend a few extra dollars on Red Line power steering fluid, despite the fact that I have quite a surplus of Maxlife ATF, Castrol Mercon V, Valvoline Mercon V, and Mobil 1 ATF.

So.....in the spirit of contributing to the global BITOG knowledge database:



While I cannot disclose the specifics of GM p/s fluid spec 9985010, here are a few observations:
  • Flash point is well within spec (shouldn't be a surprise)
  • Kinematic viscosity of this sample looks a tad bit on the low side compared to spec'd initial KV, even slightly lower than Red Line's published "typical" viscosity after shear.
  • Zinc and phosphorus both exceed the spec'd minimums by a significant margin.*


*Let's expound on that last one. Time and time again, I have read people make the argument that ATF (and sometimes ISO 32 hydraulic oil) is "good enough" for most power steering systems. I don't want to split hairs since practically speaking it may only make a marginal or even imperceptible difference (laboratory test environment vs. real-world automotive environment), but I challenge anyone to name a so-called "Dex/Merc" ATF that is rich in zinc. While power steering systems are relatively straightforward hydraulically compared to transmissions, the fluid may still be pressurized to 1200+ psi and temperatures of 125°C or higher are not uncommon.

Conclusion: Use with confidence!
 
What's the difference between this and motor oil? I wonder if you could add a quart of this to an oil sump just to up the zddp level a bit?
 
RL PS fluid is good stuff-my Hydroboost systems, namely the GMC C3500 in my sig, was burning regular fluid, turning it black, and ruined both the PS pump and Hydroboost booster. Changed the parts, bit the bullet & bought Red Line PS fluid for it, it's stayed cherry red & worked well ever since. Can't underestimate how important good brakes are when towing or hauling a lot of weight!
 
You have just disclosed the reason why I have in the past recommended Redline PS fluid for Manual Transmissions which require an ATF-like viscosity of 6.0 to 7.5 cSt fluid.


Quote:
What's the difference between this and motor oil? I wonder if you could add a quart of this to an oil sump just to up the zddp level a bit?


Mainly viscosity, friction modifiers, and seal compatibility.


And no, I would not add this to engine oil.
 
Last edited:
Originally Posted By: Linctex
wow... that's a TON of phosphorus and Zinc!


And Calcium too. Tons more than used in typical 40 grade passenger car Synthetic Motor Oils. Much closer to rear diff gear oil specs. ATF's look nothing like this with typically 100-600 ppm of major ingredients (Ca, Phos, Zn, Boron). A typical Amsoil ATF might only have a TOTAL of 1000-1200 ppm in combined anti-wear and other additives. That said, I've rarely (if ever?) had a PS pump or rack failure using ATF's for 150K-230K miles.
 
Why does the high zinc bad for engines become good for P.S. units which are no more than a low pressure hydraulic set up?
 
Bad for catalytic converters, yes, but I don't remember anyone saying zinc is bad for engines. ZDDP is a highly effective wear inhibitor.
 
Originally Posted By: NYSteve
Will be putting this in after I replace my PS pump. Redline says it's good to go for systems that call for ATF.



I seriously seriously doubt this fluid would be suitable in any AT or engine because of the additive package.

As I stated before, it works well in MT's that specify an ATF.
 
I removed the Redline PS Fluid from my 93 240. At temperatures below 0 degrees F the pump - a GM TYpe II - squealed terribly at start up. Since I winter in Stowe VT it concerned me. I now run Castrol Full Syn MV ATF and have no cold start squealing. My coldest temperature last winter was - 12 F. Car is left outside all night.
 
Molakule, If I were to do a drain and flush, would this fluid suffice to replace Honda PS fluid? Honda pumps (at least the Odysseys) seem to be notorious for self-destructing. I know the Honda fluid is typically thicker, but what characteristics would make it insufficient if it was the only fluid in the system? Thanks!
 
Sam Julier, would MOBIL 1 ATF be the same as the Castrol ATF you are using in terms of performance? 1990 and 1992 high mileage 240's, turkey baster (Dollar Tree) at hand, dubious maintenance previous owners. Thanks!
 
Originally Posted By: SubieRubyRoo
Molakule, If I were to do a drain and flush, would this fluid suffice to replace Honda PS fluid? Honda pumps (at least the Odysseys) seem to be notorious for self-destructing. I know the Honda fluid is typically thicker, but what characteristics would make it insufficient if it was the only fluid in the system? Thanks!


Some of the earlier model Honda's used a PS fluid that was 11 cSt or about a 5W30 so we have to be careful about replacing PS fluids in these vehicles. The Redline low viscosity may not be compatible with this system.

Prestone, Pyroil, and Valvoline have replacement fluids for Honda's.
 
Originally Posted By: MolaKule
Originally Posted By: SubieRubyRoo
Molakule, If I were to do a drain and flush, would this fluid suffice to replace Honda PS fluid? Honda pumps (at least the Odysseys) seem to be notorious for self-destructing. I know the Honda fluid is typically thicker, but what characteristics would make it insufficient if it was the only fluid in the system? Thanks!


Some of the earlier model Honda's used a PS fluid that was 11 cSt or about a 5W30 so we have to be careful about replacing PS fluids in these vehicles. The Redline low viscosity may not be compatible with this system.

Prestone, Pyroil, and Valvoline have replacement fluids for Honda's.

MolaKule, this is from an older post you made:

"The Redline PSF has an additive package very similar to the Honda PS fluid. The Redline PS has slightly more AW additives than the Honda PS.

The Redline synthetic fluid comes in at 7.0 cSt virgin and shears to about 6.4 cSt after repeated mechanical and thermal cycling.

Original virgin Honda PS (mostly mineral oil base) comes in at about 10.5 cSt and shears down to about 5.5 cSt after repeated mechanical and thermal cycling."


Is it still a concern considering shear in use? Redline synthetic 6.4 cSt versus Honda 5.5 cSt after repeated mechanical and thermal cycling.
 
My Honda doesn't shear its PSF to anything like that low. After an admittedly not-that-long 14k miles, it was still 10 cSt at 100C.

Curious: Where did that 5.5 cSt claim come from?
 
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