May Power Steering fluid influence steering feel?

[kilou]

Hi,

My car has now more than 220'000km and the power steering fluid (ATF type F,G) has never been changed since new. For a long time now, the steering feel is very light just as if it was too assisted. Everything has been changed around suspensions on my car (lower arms/balljoints, front struts and springs, antisway bar droplinks....) but this has not altered the steering feel. Alignment has been checked and is OK.

I'd like to know if using an ATF fluid with either higher or lower viscosity would change the steering feel. Do you think it is possible? I talk to Redline and they said after 220'000km my power steering fluid must have thinned out........would this cause an odd (light) steering feel?

 

[kilou]

Will using Redline High Temp ATF provide a heavier steering feel providing the high viscosity of this fluid compared to other ATFs?

 

[Titanium_Alloy]

PSF will definitely affect PS feel. I'm talking from my experience last week. I'll post my findings about Redline PS fluid next week when I get my UOA from Blackstone. If people from Redline told you that your fluid is finned out they are complete idiots. Their opinion, once again, proves my theory that people shouldn't buy products from basement blenders.

Here is the real thing: After 220k km your fluid is probably as thick as 20W-50 motor oil. I suggest you change you fluid using turkey buster method. Although it takes a number boring drain-refill activities it will be gentler on your system in general. There is a huge amount of sludge accumulated in your system in 220k km. To do a normal complete PS fluid change, you'll have to put through your system about 3 times its capacity. For example: if your system takes 1 liter of ATF, and your reservoir is .3 liters, you'll need about 3 liters to renew most of the fluid. Thus, you'll need to do 10 drain-fill procedures for reservoir. I suggest first time you change it with mineral based ATF and add Auto RX to it to clean it even more. After that repeat initial procedure as the first time, but now you can use (only if you want to, not required) synthetic ATF without Auto Rx. This will make your system operate at its maximum potential.

PS: I assume your car calls for ATF in your power steering. If not, use only fluid recommended by manufacturer.

Hope this helps,

 

[Greg Bohn]

quote:

---

Originally posted by Titanium_Alloy:

... To do a normal complete PS fluid change, you'll have to put through your system about 3 times its capacity. For example: if your system takes 1 liter of ATF, and your reservoir is .3 liters, you'll need about 3 liters to renew most of the fluid. Thus, you'll need to do 10 drain-fill procedures for reservoir.

---

It comes down to how much of the original fluid you want to leave.

As it turns out, a while ago I created some graphs showing how much of the original fluid is left over after a series of partial changes.

This graph (in theory) shows how much of the original fluid is left (in %) verses each iteration/change.

The Blue line is if you remove only 1/4 of the total volume each iteration. The red line is changing 1/2 each time, and the green line is changing 3/4 each time.

The next graph (also in theory) shows how much of the original fluid is left (in %) verses the volume of waste generated. For this graph, the systems 'total volume' is 10 units.

The green line is doing 3/4 of the total volume each change. The Red line represents changing 1/2 of the total volume, and the Blue line is 1/4 of the total volume.

Interestingly, the pink line is supposed to represent changing only 0.001 units out of 10 (I was thinking about a slow leak that keeps getting 'topped up').

This doesn't seem to produce as much additional waste as I would have thought (although this would require either continuous replenishment or tens of thousands of changes...)

-Greg Bohn

 

[kilou]

Nice graphs! Interesting but I feel the turkey baster method is not so efficient at removing dirt. What I'd like to do is disconnect the auxiliary drive belt and manually turn the PS pump pulley with a large spanner in order to gently pump the stuff out while pouring new fresh fluid in.

Titanium Alloy, do you think that if I use a thin fluid, I may get a heavier steering feel compared to thick fluid? I really want to have my steering heavier because it is way too loght now and this becomes really annoying (and I do not have mechanical problems that may do this).

My car use ATF for power sterring. However I went to my dealer to buy some of this ATF but they said the part number has been replaced by a new fluid which is Pentosin CHS11 or something like that. I worry if I can use this new fluid providing my system has run on ATF for 220k km!!! What about the seals?

[ June 21, 2004, 01:12 AM: Message edited by: kilou ]

 

[Titanium_Alloy]

quote:

---

Originally posted by kilou:

Titanium Alloy, do you think that if I use a thin fluid, I may get a heavier steering feel compared to thick fluid? I really want to have my steering heavier because it is way too loght now and this becomes really annoying (and I do not have mechanical problems that may do this).

My car use ATF for power sterring. However I went to my dealer to buy some of this ATF but they said the part number has been replaced by a new fluid which is Pentosin CHS11 or something like that. I worry if I can use this new fluid providing my system has run on ATF for 220k km!!! What about the seals?

---

I don't know for a fact, but by my personal experience I can tell that thinner fluid caused a bit heavier feel in my car. I don't know how your car will react to it. However, changing fluid will probably restore steering feel very close to original. Actual power steering "feel" depends mostly on how your PS system is set up. Some cars are tuned to a heavier feel (for sporty driving) others designed for a lighter action (for comfort and easy parking). 2 cars with the same power steering system components might have a different steering feel. Latest in steering design is a variable effort steering, new BMW 5 series seems to be a leader in this area with "active steering system."

I would be leery to use new Pentosin in your car. It might be fine, but most likely will result in power steering leaks (also depends on condition of your PS system in general). In that sense you're right that old seals might just leak as **** . Pentosin is very thin compared to ATF fluid. I would just try to find required ATF. If you can't, I think that you should go with a regular Dexron III.

Regards,

 

[Titanium_Alloy]

quote:

---

Originally posted by kilou:
To my knowledge, all oils become thinner with increasing service time, not thicker! So what Redline told me about my Power Steering ATF that have thinned out after 220'000km makes sense, no?

Moreover it is likely that thin P/S oil should help the steering and thus cause a light steering feel as Pentosin CHS 11 (very thin) is recommended in my P/S system for Scandinavian countries. In other words, shouldn't I use a thicker ATF to get a heavier steering feel (I'd like to have the P/S even more heavier than original)?

---

Please read in more information about oil behavior in a long run. Such information is available on the net and had been discussed on this site a number of times. Oils do become thinner with use only in a relatively short period of time. Later they start to oxidize, and as a result become thicker.

Here is the quote from v8sho.com ( http://www.v8sho.com/SHO/psflush.htm ):


V6 SHO's are known to have issues with power steering pumps if the fluid is not changed. FOMOCO does NOT list changing the power steering fluid as part of normal PM but normal use will over time change power steering fluid to tar and pump replacement is very expensive. After 50,000 miles my PS fluid tested 60W when it should be 20W, and was 36.7% oxidized. Burned up Power Steering fluid has carbon crystals which is abrasive. In my case I simply sucked out the old PS fluid and toped of the reservoir with fresh ATF fluid. If done every 10,000 -20,000 miles this should be sufficient. - Timothy Wright (AKA "Buford")


He is rather accurate about the description. I don't think that it should be changed every 10k-20k miles on a regular car (maybe 30k-36k miles or 3 years). But then again it depends on a specific car, driving conditions, and driving style. Just as with motor oil some cars are harder on PS fluid others are easier.

Use whatever is recommended in your system. You might want to call manufacturer and ask them directly what PS fluid to use and where can you buy it. They'll tell you for sure.

I hope that clears some of your doubts about PS fluid.

Regards,

 

[unDummy]

I'm a believer of regular PS fluid changes. There is a lack of filtration for this fluid. A pint of fluid is too cheap not to change every 6 months or so. And, a inline filter can be added if you are too lazy to do simple maintenance.

All it takes is one pump/rack failure and you will do everything possible to avoid that replacement in the future. That being said, I haven't lost a rack or PS pump in 8 years and I tend to be an abusive driver at times.

I perform the siphon/refill at every oil change. This removes a reasonable amount of fluid which will just about always remain clean looking.
I don't care for the turkey baster method.
http://www.motorvate.ca/mvp.php/702

What I use is gravity and a long hose(leftover from the fishtank airhose plumbing). If the hose doesn't reach to the bottom of the reservoir(which mine didn't), I used a basket/soccerball filler. This extension will plug directly into the hose and allow siphoning to the bottom. It'll also work great with the other overly neglected fluid(DOT3/4).

 

[kilou]

Thanks for your replies. I know my car calls for ATF type F,G in power steering. What is the difference between type F and type G ATFs? I've only seen certifications like Ford Mercon etc but not type F,G......

I found that it should be possible to manually turn the PS pump pulley with a large spanner (after having disconnected the auxiliary drivebelt). Do you think it is a good solution to do so or is it risky? I know there are plenty of other methods but I'd like to efficiently remove all the crap in 1 time.

 

[Titanium_Alloy]

ATF type F is a very old ford ATF specification. It doesn't contain any friction modifiers as far as I know. It is still being sold here in US, though not in large volumes. I've never even heard of ATF type G. It might be approval specification like Dexron III-G, or Dexron III-H, and etc. These letters ususally are not shown on the package and bottle just says Dexron III. I'm not sure if that's the case for your application. Dexron/Mercon fluids are quite different from type F. I don't know if you can use them instead. I don't see any problem with it. PS system has nothing like bands and clutches in transmission. Thus I don't think it would cause any problems.

Regards,

 

[VaderSS]

First I had heard of it too, but it appears to be a valid spec;
http://www.valvoline.co.nz/prod011.htm
Ford specification M2C33G(Type G) or 33F(Type F)

 

[JohnBrowning]

Yes steering feel will be affected. THe viscosity is only part of the answere. THe frictional charteristics and flow charteristics are more important. When I put Redline C+ ATF and Amsoil Universal in various power steering systems I noticed an imediate improvment in smoothness. THe Redline C+ made a huge difference in my Dodge. It was lighter, smoother had less lag and functioned much better in my cold climate. It also made the pump extremely quite. THe Amsoil did the same thing put not to the same degree. I suspect that Redline had a beefier additive package.

 

[kilou]

To my knowledge, all oils become thinner with increasing service time, not thicker! So what Redline told me about my Power Steering ATF that have thinned out after 220'000km makes sense, no?

Moreover it is likely that thin P/S oil should help the steering and thus cause a light steering feel as Pentosin CHS 11 (very thin) is recommended in my P/S system for Scandinavian countries. In other words, shouldn't I use a thicker ATF to get a heavier steering feel (I'd like to have the P/S even more heavier than original)?

 

[tdi-rick]

quote:

---

... if using an ATF fluid with either higher or lower viscosity would change the steering feel. Do you think it is possible?

---

I was wondering about this recently.
I flushed one of our cars thoroughly 10 000km ago with 4.5 litres of fresh fluid (Caltex/Texaco Cold Climate/Land Rover PAS 14315)

As the stuff that came out was pretty horrible looking (supposed to be green, was black) I've dropped some A-RX in it and will flush it again soon.
The big surprise is that the steering has become lighter. At first I thought I was imagining it, but it definitely has changed, although not for the better.
I want some weight back !

Apart from things like caster and tyre section, pressure and type, wouldn't the operating pressure of the system have to be altered to change the weight/feel ? and don't they work, like most pressure pumps, on a pressure relief valve, so that the maximum working pressure is fixed, regardless of the fluid viscosity ?
Therefore, a change in viscosity shouldn't alter the weight of the steering. at least this is how the oil pressure pumps used to work on the race cars I used to work on. You could go from a 20w-50 to 0w-50, yet have exactly the same oil pressure at maximum RPM. Idle was a little different 'though.

So, why on earth has the steering changed since adding the A-RX ?

Hmmm after re-reading JB's post immediately above, could this be the answer ?

Rick.

[ June 24, 2004, 04:09 AM: Message edited by: tdi-rick ]

 

[kilou]

I've contacted Volvo to know what type of fluid to use in my PS system. As I said before, my car calls for (and has always run on) ATF type F,G. However Volvo told me that the part number for ATF type F,G has been replaced by Pentosin CHF 11S. This fluid is green while my ATF is red. Do you think that I may mix the Pentosin with my old ATF (turkey baster method) or is this risky? If Volvo has cancelled the old ATF, the new Pentosin should be compatible no?

 

[kilou]

The problem is that I'd like to have a heavier steering feel, not a lighter one and it seems that changing the PS fluid for a fresh one (maybe no matter the viscosity) will make the PS even more light

 

[kilou]

I've contacted Volvo to know what type of fluid to use in my PS system. As I said before, my car calls for (and has always run on) ATF type F,G. However Volvo told me that the part number for ATF type F,G has been replaced by Pentosin CHF 11S. This fluid is green while my ATF is red. Do you think that I may mix the Pentosin with my old ATF (turkey baster method) or is this risky? If Volvo has cancelled the old ATF, the new Pentosin should be compatible no?

 

[kilou]

Today Volvo told me that ATF type F and Pentosin CHF 11S fluids can be mixed! Really?????????????

Look at this:

"Pentosin CHF 11S

Synthetic Oil for central hydraulic systems, level control, hydro pneumatic suspension, shock absorber, power steering. Range of operation: -40C to +130C, especially recommended for countries of cold climate. Close container after use. Very Important: Pentosin CHF 11S should not be mixed with Pentosin CHF 7.1 or any other hydraulic oil . BMW Teile Nr: 81 22 9 407 758 USA BMW Teile Nr: 82 11 1 468 041 Porsche Teilenummer: 000.043.203.33 Olive Color fluid (Olive color, is defined as "yellow green")

[ June 25, 2004, 12:09 PM: Message edited by: kilou ]

 

[JustinH]

My new fords use mercon V in the transmission and Mercon III in the power steering rack.

Once a year I buy couple five quart jugs of supertech brand ATF, and drain the bottle and refill over and over again to flush the system.

Its real cheap insurance for what a powersteering rack costs.