Alternative fluid for SLS ('82 300TD)
 

I will be getting my TD back on the road, and would like to do a complete fluid change on the SLS. Do I really need the special fluid that MB calls for? I would think that the hydraulic system is no different than that of a tractor, and wonder if tractor hydraulic fluid would work? I have a couple gallons of the stuff on hand. The SLS fluid is available from our sponsor, but it will take a couple days to get here, and is expensive. The BIG question(s) is(are): Will standard hydraulic fluid harm the SLS system in any way? Is there any ingredient in the SLS fluid that makes it proprietary that regular hydraulic fluid does not have and/or need? Since these systems are so expensive to maintain and repair, I don't want to save a few dollars now, only to spend many more later. Also, I don't know the health or the lack thereof of the SLS in my car. I bought the car 8 years ago, and am just now getting around to working on it. Thanks, Rich

I believe it must be an ester based oil, not mineral, otherwise the seals will react and start to leak?

The Castrol version; seems to be petroleum based.


Product Data
Hyspin™ ZH-M
Hydraulic oil
Description
Castrol Hyspin™ ZH-M (previously called Vitamol™ ZH-M) is a special central hydraulic fluid, formulated with the highest
quality base oils together with a carefully selected additive package. This formulation ensures reduced hiss and crunch
noise and provides enhanced machinery protection due to excellent corrosion protection. The favourable viscosity index
together with the low evaporation loss, guarantees a functional safety over a wide application range.
Application
Hyspin ZH-M was developed specially for the motor vehicle industry, particularly Mecedes-Benz (MB-sheet 343), for use
as a central hydraulic fluid.
Page 1 of 2

Typical Characteristics
Name
Method
Units
Hyspin ZH-M
Colour
ISO 2049 / ASTM D1500
-
1
Density @ 15°C / 59°F
ISO 3675 / ASTM D1298
kg/m³
865
Kinematic Viscosity
@ -40°C
@ 20°C
@ 40°C
@ 100°C
ISO 3104 / ASTM D445
P-VW 1408
mm²/s
3800
33.7
16.4
4.11
Viscosity Index
ISO 2909 / ASTM D2270
-
161
Pour Point
ISO 3016 / ASTM D97
°C/°F
-45/-49
Flash Point - open cup method
ISO 2592 / ASTM D92
°C/°F
157/315
Acid Number
ISO 6618 / ASTM D974
mg KOH/g
2.3
Corrosion Test VW-TL 731
-
-
fufilled
Volatility - Noack (at 100°C)
DIN 51581-1
% wt loss
1.4
Subject to usual manufacturing tolerances.
This product was previously called Vitamol ZH-M. The name was changed in 2015.
Hyspin™ ZH-M
20 May 2015
Castrol, the Castrol logo and related marks are trademarks of Castrol Limited, used under licence.
This data sheet and the information it contains is believed to be accurate as of the date of printing. However, no warranty or representation, express or implied, is
made as to its accuracy or completeness. Data provided is based on standard tests under laboratory conditions and is given as a guide only. Users are advised
to ensure that they refer to the latest version of this data sheet. It is the responsibility of the user to evaluate and use products safely, to assess suitability for the
intended application and to comply with all applicable laws and regulations. Material Safety Data Sheets are available for all our products and should be
consulted for appropriate information regarding storage, safe handling, and disposal of the product. No responsibility is taken by either BP plc or its subsidiaries
for any damage or injury resulting from abnormal use of the material, from any failure to adhere to recommendations, or from hazards inherent in the nature of the
material. All products, services and information supplied are provided under our standard conditions of sale. You should consult our local representative if you
require any further information.
Castrol Industrial, Technology Centre , Whitchurch Hill , Pangbourne , Reading , RG8 7QR , United Kingdom
www.castrol.com/industrial
Page 2 of 2

Thanks Frank! That is probably more than I need to know.....Rich

Just as with engine oil, ATF, coolant, or any other fluid, I would use only a fluid that meets the relevant MB standard. This LM product carries MB 343.0 approval:

https://products.liqui-moly.com/central-hydraulic-system-oil-2300-1.html "For hydraulics in Mercedes-Benz passenger cars e.g. ride-height control, hydropneumatic suspension and hydraulic plants from ASD, 4Matic and tops."

As for using "tractor fluid", I'd be hesitant to use anything unknown like that. The risk in a hydraulic system of using an incompatible fluid, is that all the seals rapidly degrade and fail, and the system begins to leak like a sieve. You don't want that.

I tried tractor hydraulic fluid. Worked for a couple months then my freshly rebuilt leveling valve started leaking all over.
After second valve rebuild I stuck with the correct fluid and its been working fine for the last decade.

I think the key difference is that the specified fluid has more stable viscosity as temperature varies. In a pinch, I've used Pentosin 7.1 in a 124, but I'd recommend sticking with the factory stuff. The later cars (210 and newer) used a synthetic fluid which doesn't mix well with mineral oils.

Well, I just bit the bullet and ordered 4 quarts from our sponsor. I am just hoping that the rest of the hydraulic system is sound. I don't want to waste $10 a quart fluid!

A thought for others, a Chrysler TSB said to change power steering fluid to ATF+4 when doing major work on the system, even in older cars (my 1960's I assume). The reason was to minimize a whining noise in long minivan hoses, which is a common problem with SLS hoses in 300TD's. I think Chrysler similarly put plastic disks in the hoses to stop whine. Most ATF+4 brands are fully synthetic. But not much cost savings, ~$5/qt vs $10/qt for M-B fluid, so why risk it.

Exactly. Yes, the correct fluid is expensive. But replacing a bunch of now-leaking hydraulic components because you used the wrong fluid is even more expensive. Plus how often do you change this fluid? Years, I'd bet, so the cost *over time* of the correct fluid is actually quite small.

Shell Tellus T22

I bought the 5 gal when I first started working on my 85 300TD sls system and am SO glad I did. The fluid in it looked like old motor oil when I got it and the rear sagged, so it was pretty bad.

Over the years I've had to replace several components: valve seals, both spheres, 1 ram (used), ALL at different times. If I had to buy fluid to flush out the old crap and everytime I fixed something, it would have been much more expensive.

Fluid stays clean now and nothing has leaked in years. Still have over a gallon left.

Do some research though, T22 might not be the best choice if you live in a freezing environment like Canada. I think the stock fluid is a little bit thinner.

I originally thought that all hydraulic oil (fluid) does the same thing, so why not use what is available? BUT- the consensus here is that ONLY factory approved fluid should be used. I ordered 4 quarts from our sponsor, and am hoping I have no leaks after the system is up and running. If I did use generic hydraulic fluid at first and had a leak(s), I suppose I would not know if the leak was caused by old seals that would have leaked regardless of what fluid was used, or because of using the wrong fluid. If I knew more people that used generic fluid without issues, I might have taken a chance on the fluid I have. We shall see. I should get the parts (fluid, hose, gasket etc) in a few days. Stay tuned.......Rich

To me a leak would be a minor possibility compared to other things.. MB is very specific about this particular thing...
As an example... I think it was moderator JimSmith who pointed out that some wrong trans fluids would eat up the synchronizer .. made from brass or something.. ... That is way worse than just an external leak..
IF the proper fluid is available for $10 a quart.. or liter ... I think this is the time to go with MB's instructions...

Using the right fluid is always a good decision. I did a lot of reading before going with a different hydraulic fluid. I knew I needed a lot , so that's why I went 5 gal.

BTW, I only use approved PS fluid even tho many folks use the red atf.

Hydraulic fluid is definitely not all the same. While in the military, I know it was eons ago, we always had to battle leak issues for aircraft that used Skydrol. Parts people were notorious for giving us O-rings that should work "because they were the same size". After a major hydraulic leak on the engine-driven pump, in flight, many select words were used to demand the correct part.

True, this isn't an aircraft, but who knows what major grief this will cause at the most inopportune time. That's when all of my failures seem to occur.