Power Steering Fluid vs Dex/Merc vs Type F

[thesameguy]

I know the XR was originally specified to use Type F in the power steering system, but I'm wondering if anyone has converted to some other fluid and has a recommendation... Keeping Type F around kinda sucks and it's getting difficult to find! Switching to a modern fluid seems like a good idea in general, and since I have a new rack, a new pump, and shortly all the rubber will be new, I think there can't be any roadblocks to switching. Anyone have any thoughts on the matter?

[zxr250cc]

Hi,

I pumped all the old dark, dirty Type F out of my '86 models rack, flushed out the rack and hoses with a couple of quarts of generic Dex-Merk (I drove it for about ten miles to fully flush the new fluid throughout and then drained it all out) and put Max Life Dex-Merk ATF fluid in the steering pump so that I have the same fluid in the transmission and steering like in my Taurus. It is working fine with about seven or eight hundred miles driven so far. You can turn the pump by hand or spin the motor with the coil lead off so the motor won't start to pump out the fluid. I like the Max Life ATF as it is a full synthetic fluid with additives to maintain the seals and loaded with friction modifiers to match a very wide range of cars. I don't work for Valvoline, just like the fluid.

Cheers

[Mike McCreight]

Mobil 1 synthetic ATF and a bottle of Lucas.

[DPDISXR4Ti]

This is what I plan to do....
http://www.allfordmustangs.com/forums/2 ... e-fix.html

I have already done the Saginaw pump swap on my F-150. I run Valvoline PS fluid with that setup and it works fine.

[thesameguy]

I was considering a whole pump swap, but I just don't have the time or energy for that right now. The factory pump was cheap and I replaced the rack a couple years ago (2,000 miles ago?) so the whole system will basically be new. I'm having the high pressure hose rebuilt right now.

At various points researching this, I've really been unable to quantify the difference between "ATF" and "PSF." I think PSF has had worse controls over the years, and there are massive variances over time & amongst brands. ATF has evolved but is very well documented, with probably the biggest variance being increasingly lower viscosity over time. Type F is ~7.5cSt and that's similar to most power steering fluids, but Dex VI is down around 5.5cSt and some newer fluids even lower. Beyond that, they're just hydraulic oils with various additives, and I don't know how to quantify that!

Application-wise, power steering systems vary dramatically from transmissions in that power steering systems are intermittent, high-shear and high-friction systems and transmissions are far more stable operating environments. In my head, it seems like a dedicated PSF with extra stability and extra anti-wear additives would be the preferable choice to ATF. The fact that PSF and the factory-specified Type F share some viscosity attributes seems attractive.

Mike, how come the Lucas? Do you have leaks or is it preventative? I ask, because I can't help but wonder if ATF+Lucas just results in effective PSF - a hydraulic oil with a high viscosity, anti-wear attributes, and shear resistance!

I'm tempted to try Redline PSF - I use it in my motorhome... that thing beats up PSF like you wouldn't believe. A tiny pump running hydroboost brakes for a 16000lb brick! Other things I tried, stuff that works in the race car, boiled readily. The Redline PSF has remained very stable.

[Mike McCreight]

The Lucas made the pump run quieter and completely removed a slight notch in the rack.
It's magic...
Tempted to try your motorhome trick. Anything that will help the braking in that thing is worth a try!

[thesameguy]

The fluid was only part of the equation. I also installed a cooler between the autopark return and the pump:



The improvement was dramatic. I first encountered the problem coming over the Grapevine, where there is a long slow decent where you're on the brakes a bit, then a really fast, steep decent where half the road is nervous automobiles and the other half is semis with their brakes on fire. Getting to the bottom it was clear I'd lost substantial brake assist, so I flushed the system and put some known-quantity Valvoline synthetic in. The first time I took the thing over the Sierras I ran into the same problem when we hit traffic coming down off the summit - after a multi-mile decent on the brakes, I spent 45 minutes in stop & go and again toasted the fluid. When I got home, I flushed it with Lucas's own PSF, but next time through the Sierras had the same problem. After that, I installed that B&M transmission cooler and switched to Redline - the other option was Royal Purple - similar specs, the Redline was available locally. Since then, I have had zero brake issues. I can actually be pretty rough on them and they don't give up. The PS system in the P30 is awful, totally underdesigned. Actually, everything about the P30 in general is underdesigned.

[morlynon]

I heard that NAPA 75-205 Ford Type F transmission fluid is a good alternative. Does anyone have personal experience with this product?

[Mike McCreight]

I IMMEDIATELY recognised the view under your MH.. Right down to the bags.
Didn't most of the P30 chassis wind up as postal trucks? Here in Canada that was the case.
I don't encounter many overly long hills, and the ones I'm familiar with, I approach at just moving speed, esp. when towing. Getting to the bottom, approaching terminal speed can be very exciting.
I had a F hose go on me, internally, when some "wow, should you really still be driving?" type decided to pull out in front of me on the Trans Canada without bothering with the accelerator. Maybe he just didn't see the 32' MH and cargo trailer attached coming. Happily the hose held, but wouldn't allow drainback, and the caliper stuck. The remainder of that trip was fun. Happily, the NLA from GM hoses were easy to find at Rock Auto.
I've since upgraded the horns.
I have a big PS cooler here somewhere, and there's LOTS of room under there, thanks for the tip!!!

[thesameguy]

I know the P30 was used as the basis for a lot of commercial vehicles - the P30-based motorhomes are derogatorily referred to as "bread trucks" because in the US they made up the vast majority of the Hostess et al delivery fleets. Around here, there are still lots of them on the road as catering trucks (aka roach coaches). Most of the last mile mail delivery is with Jeeps (maybe made by AM General), but I'm not sure what the heavier duty stuff is - could very well be P30s.

If you're thinking about putting a cooler in there, I'll show you the other thing I did at the same time:



Right on top of the autopark valve is a fitting with a brake bleeder in it. Makes getting the air out of the autopark system infinitely easier. Obviously it's an unusual thing to have to do, but I was so readily wrecking power steering fluid I wanted an easier way to do annual fluid exchanges. I used it one last time to bleed after doing the cooler & Redline - it's been unused for two years since.

[zxr250cc]

Hi,

I think the Mobil and the Valvoline are both better for additive packages and temperature tolerance than Type F. Any of you ever read oil data on Bob is the oil guy site? (BITOG)

https://www.bobistheoilguy.com/forums/u ... _Maxlife_A

I find a lot of useful info there.

Cheers

[thesameguy]

Definitely agreed - really, anything in 2018 should be better than Type F from that perspective, but there are potential other concerns when messing with hydraulic fluids. Viscosity, anti-wear packages, and detergents or other additives that could harm seals are all things to be aware of. My thought process is that anything rebuilt these days (pump, rack, etc.) is going to be made with synthetic rubber parts that will probably be immune to harm from the "wrong" fluid, but that still doesn't address viscosity or additive packages. So, at this point I'm not worried about wrecking anything, I just don't want to do the work twice.

[thesameguy]

Got my new pump installed, and got my rebuilt high pressure hose back:



The old one was probably original, and heavily cracked. It's very possible the inside was falling apart too, but who knows?

I agonized over it a bit longer but ultimately filled the thing with Valvoline Maxlife ATF. I did a few fill/run/drain cycles to try and get all the old crap out, but I suspect there is still some Type F and Lucas stop leak in there as the fluid is a bit purple. I will run it for a few weeks and then maybe do some additional flush cycles.

I haven't driven the car yet, but the new pump definitely cured the notchiness I was feeling before. Obviously the old pump was old. I still have a pretty loud whine when turning the wheel (front tires are off the ground) but I think that's unavoidable with this low-tech pump. It's probably inaudible inside the car and in motion, but we'll see. I was hoping for better, but you can't polish a turd.

[zxr250cc]

Hi all,

A lot of the more modern cars need to have the wheels on the ground for the power steering pump to function properly and pump fluid through the rack when turning the wheels back and forth. I am not sure about a Merk but it might be the same... ??

Cheers

[LITTELHAWK]

I've been running Dex/Merc in mine for over a year now with no problems. The only problem I could see it causing is a leak if your seals are too worn to hold the lighter fluid.