Power steering fluid viscocity?

[buck91]

All things being equal, would a power steering system tend to operate with any benefit from running a fluid on the thin end of the spec range or thick... or irrelevant? Specifically, I'm considering the use of Maxlife ATF (which is now an LV fluid that states its fine for dex/merc apps) in a system spec'd for mercon. I have a big jug of Maxlife, but it is more expensive than buying some generic dex/merc.

 

[Colt45ws]

I thickened mine which had syn ATF with some 5W50 racing oil for stiffer steering. Not a lot, a few ounces to bring it up to a 30 weight, from a 20 of ATF.

 

[oldhp]

2010 Ranger, I did 1qt worth of drain and refill over several times with Mercon V. It helped some but the biggest change, easier steering, was when I added 1oz Red Lubegard. Don't know if this helps or hurts for your question.

 

[Garak]

I wonder how sensitive some of them really are. Previous iterations of my G37 called for generic Dexron. The cap even says so. The manual calls for Dexron-VI, which, of course, was current at the time. Nissan PSF is acceptable. Pentosin claims their high end stuff is compatible, too. So, maybe it just doesn't matter as much as we like to think, at least in a number of vehicles.

 

[Shannow]

Ford in Oz use Mobilfluid 424 in the power steering systems...it's an 80W Dexron.

I've used it to quiet GM pumps that are in the way out for a few thousand km.

 

[Shannow]

But of everything I've tried, this is the best...

http://penriteoil.com.au/assets/pis_pdfs/PAS FLUID AUGUST 2016.pdf

 

[Jetronic]

there's also Total fluide DA with a VI of over 300.

 

[Shannow]

Originally Posted By: Jetronic
there's also Total fluide DA with a VI of over 300.


Is that like the stuff used in the Citroen suspensions ?

 

[Jetronic]

I don't think it is, but that stuff is sold under 2 names: Fluide DA and another which I can't remember right now. Fluide DA stands for "Fluide Direction Assistée" or "Powersteering fluid", btw.

I'll probably switch to that stuff at some point for the hydraulic actuation of my gearbox.

EDIT: just looked it up, and the other name it's sold under is FluideLDS, and that's for the suspension indeed.

same specs and colour on the spec sheet, different bottle. Price is comparable, I suppose they diferentiate so people aren't tempted to put ATF in or other hydraulic oil in either application.

 

[Shannow]

Cool,
Penrite have one, VI 342
http://penriteoil.com.au/assets/pis_pdfs/LDAS - MAY 2017.pdf

Used to be in the shops, but not ATM...

 

[Jetronic]

Sadly I've never found Penrite oils here in Europe.

 

[Popsy]

Originally Posted By: Jetronic
there's also Total fluide DA with a VI of over 300.

OMG
And I thought "fluide DA" was [censored]... Costs 5€/L here, didn't seem very heat resistant in my car.
(BTW my car manual states either Dexron II or sae10 oil)

 

[69GTX]

The Merc/Dex is quite cheap. In fact, even the semi-synthetic Mercon V (7cSt) can be bought for $4.25/qt (SuperTech) at W/M...and it shears down half as fast as old Mercon. I'd stick with the mfg's recommended viscosity.

The LV fluid is probably fine in a Wisconsin winter. Not sure I'd want to lose that extra viscosity (7.4 vs. 5.8 cSt at 100 deg C) during the hot summer.

 

[Linctex]

I typically use whatever ATF is just lying around.

I have used 0W-20 as well, seems to work fine.

 

[Jetronic]

Originally Posted By: Popsy
Originally Posted By: Jetronic
there's also Total fluide DA with a VI of over 300.

OMG
And I thought "fluide DA" was [censored]... Costs 5€/L here, didn't seem very heat resistant in my car.
(BTW my car manual states either Dexron II or sae10 oil)


Which car and what symptoms?

The flash point is low, the penrite seems to do better in that regard. But for hydraulic actuation, the flash point is not nearly as important as a low viscosity at all temperatures.

 

[Popsy]

Barchetta, with ridiculous ps cooling loop => noisy pump after some spirited driving, I guess fluid was too hot, and ps pump not that "fresh". Actually it is better after several drain and fill.