Power steering fluid to fill up manual tranny??!

[MMamdouh]

i have heared this strange thing from my mechanic... he said that tit is better to fill up a manual tranny with Power steering fluid rather than this very heavy oil it has got in.

he says that the power steering oil is designed to handle pressure (can't argue with that) and it is more fluid so it will spread much better in the tranny and lubricate the gears better (can't argue with that either) and he also said that this replacment solved whining problems when engaging 5th gear on some cars he was working on.

frankly i have no idea about that guys... the PWS fluid IS designed for working under pressure and IT IS more fluid than the regular tranny oil we have in out transmissions (i am talking about Woos that are assembled in Egypt) but i am not going to try that on my car... not just yet.

what do you think guys? anyone ever heard of such thing?
is that a good idea to do?
will the PWS fluid be durable and effective as the regular tranny fluid?
is it going to be worth the effort to flush the old oil and buy 2 liters of PWS fluid??

need your advice guys.

MMamdouh

[chronoti]

are you talking about an auto or a manual? i know there was a series of toyota transmissions that actualy used dextron, oh power searing fluid in anything but a honda is normal dextron/mercron fluid.

um if you talking about a manual i hear good things about gm syncomesh.

[genie47]

Not a good idea at all.

There are subtle differences between ATF, PSF and GL4 gear fluid which manual tranny GMDAT cars use.

ATF of which DexronIII is used in GMDAT cars are fluids at 7.0 to 7.75 cSt Kinematic Viscosity (at 100 C) and a 40 C viscosity of 35 cSt. Flash points are about 367 F, pour points are -60 F, and sulfur is 2200 ppm with phosphorus being 620 ppm. The SUS viscosities are 17,500 cP at -40 F and 1,350 SUS for -10 F.

Incidentally, the PSF used in GMDAT cars is Dexron III. This simplifies inventories.

A point to note is that ATFs are friction-modified. For Dexron's case, as spinning speed increases, the coefficent of friction increases. So at low speed low Cf, and at high speed high Cf.

To quote Lubrizol:

ATF is the most complex of all lubricating fluids. Not only does it have to reduce friction to prevent wear like all lubricants, but it also has to allow a certain level of friction so clutch materials can engage. Since most OEMs use proprietary frictional materials, virtually every ATF is OEM-specific. In some cases, they're transmission-specific. In addition, ATFs must be compatible with all transmission components, operate at both low and high temperature extremes, and maintain constant performance for extended periods.

GL4 gear fluid on the other hand is different. GL4 and GL5 are basically the same except that GL4 has a lower additive treat rate at 1-2% while GL5 has 5-6%. Higher additives can attack soft metals like brass on gears and synchros. GL4 (and 5) have better displacement and grip. Please note that transmissions do not have the same torque as differentials.

It is all pretty complex. Someone asked if he can use a 20W50 to replace a GL5 gear fluid and the answer is pretty much summed up here:

http://theoildrop.server101.com/ubb/ult ... 6;t=000577

Quoting Molakule:

Gear teeth are under high shear and rolling stresses and need a film or coating to protect them from these high stresses. There are not enough additive levels in motor oils to keep the parts coated under these high loads.

Lets assume the PSF you use is not Dexron but Pentosin derived PSFs that the VAG cars and SAABs use of which can be found as those regular OTC PSFs sold by Royal Purple as MaxEZ, you are still going to get the problem of not having enough addtives to keep parts coated under high loads.

Then there are some special PSFs that meet GL4 specs. Redline is one of them. I don't think there is another PSF that has GL4 specs anywhere besides Redline for that matter.

For further reads, I will recommend the following links to BITOG. They are very heavy reading. But the bottom line is not to use fluids intended for other purposes. The use of ATFs as PSF is pretty much standard issue because power steering systems are very simple. Just a vane pump needing some hydraulic fluid to lubricate and move things. I have used Toyota's T-IV as my PSF with no problems because I can get it much cheaper than synthetic blended Dexron IIIH. ATFs do not usually attack metals.

http://theoildrop.server101.com/cgi/ult ... 4;t=000225

http://theoildrop.server101.com/ubb/ult ... 4;t=000226

Below is a post by the same author on extreme pressure additives.

http://theoildrop.server101.com/cgi/ult ... 4;t=000227

[MMamdouh]

so in the end it is a bad idea... right? the manual states i should use W80 fluid in my tranny so i guess this is another sign that the ATF idea is not that good.

MMamdouh

[chronoti]

so in the end it is a bad idea... right? the manual states i should use W80 fluid in my tranny so i guess this is another sign that the ATF idea is not that good.

MMamdouh

yup

[daftmajin]

so in the end it is a bad idea... right? the manual states i should use W80 fluid in my tranny so i guess this is another sign that the ATF idea is not that good.

MMamdouh

Don't try it. ATF in the PS is ok but has to be dangerous to use on a M/T.

[genie47]

Using GL5 gear lube in a gearbox that specifies for GL4 is also a pretty bad idea.

[MMamdouh]

found out that the opel cars that had ATF fluid in their tranny was a miss conception... those cars came from Europe and had very low grade viscosity tranny fluid that is red as PWS fluid... this is because in Europe it is way more cold than here and cars require less viscosity in their tranny oil to operate properly

our geniuses (AKA Mechanics) here thought that that fluid is ATF and started using it in cars running on our streets.

MMamdouh