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J2Jake · 10-25-2017, 07:44 PM

Replacing my Sheppard steering box with a TRW. My owners manual says Dexon lll, have been told it should be hydraulic fluid. How does one know for sure?

96 Wideglide · 10-25-2017, 07:47 PM

What color is it?

CountryB · 10-26-2017, 04:03 AM

Dexron is considered a hydraulic fluid.
On the Allison Transmission forum there is an engineer posting that was the guy who wrote the Allison oil specs, and he says the Allison brand Transynd is superior to Dextron in every way - and can/should be used for hydraulics (like HWH system) and steering.

There may be other products equally good (but as Allison guy he knows/recommends his products) - but point being the automatic transmission fluids "are" hydraulic oils.

My Owners manual says use "Transynd" in the transmission and Dexron III in the hydraulic system.

J2Jake · 10-26-2017, 07:45 AM

Ben, can't really tell. Due to it being low I did add a little III. When I remove the box I intend to allow as much fluid to drain as possible.

Mike Thanks, from your info seems it doesn't matter. Jake

azpete · 10-26-2017, 08:13 AM

the reason hwh uses dexron 3 is that it is available everywhere. the type of fluid used in the hwh system can be any of the dexron 3 or mercon. just dont use old type f.
transynd is also fine, but it cost way more. if you already have the red fluid or the clear hwh fluid in your system, just use the walmart or auto zone dexron 3 fluid.
if you are not sure what you have, and have never changed it, use dexron 3.

wa8yxm · 10-26-2017, 08:22 AM

Dextron III IS in the class of fluids called Hydrauilc.

And it is the one specified. Transyd can also be used.

There are two major differences between generic "Hydraulic" fluids and Transmission fluids like Dextron

ONE Dextron is VERY HEAVY DUTY.. The kind of service it is designed for is far beyond what say
"Jack oil" can handle.

2: It is way easier to fijnd (Any gas station)

J2Jake · 10-26-2017, 08:33 AM

All, this is for my Power Steering. Nice to know about HWH though. Thanks for the info/help. Jake

nehog · 10-26-2017, 03:44 PM

Quote:

Originally Posted by J2Jake

All, this is for my Power Steering. Nice to know about HWH though. Thanks for the info/help. Jake

Either should work. Another 'note' is that ATF has better cold weather characteristics compared to regular hydraulic oil.

Were this mine (and it may be in a few days...) I'd use ATF. But you can check color sometimes and see what is in there. Odds are however, it will just look somewhat black from the rubber hoses.

xydial · 10-28-2017, 08:23 AM

Quote:

Originally Posted by J2Jake

All, this is for my Power Steering. Nice to know about HWH though. Thanks for the info/help. Jake

Interesting, but my service manual states the power steering is " filled with 15W-40 motor oil from the factory".

RobRoy · 10-28-2017, 10:56 AM

Quote:

Originally Posted by xydial

Interesting, but my service manual states the power steering is " filled with 15W-40 motor oil from the factory".

I have found my fair share of mistakes in the print version of the factory service manual on my coach and IMO there is not a chance in the world that your power steering unit uses motor oil as the correct fluid.

All I can say is "Enter with caution"

Mr_D · 10-28-2017, 11:04 AM

There has never been a fluid named "Dextron", it's "Dexron".
But I've seen it misspelled in published Allison papers where you think it would be corrected.

96 Wideglide · 10-28-2017, 07:12 PM

Quote:

Originally Posted by xydial

Interesting, but my service manual states the power steering is " filled with 15W-40 motor oil from the factory".

Plenty of older threads on this forum 07'-09' stating Monaco used motor oil in their hyd system! Mainly models from Diplomat / H.R Endeavor, down.

67fisher · 10-29-2017, 03:28 AM

Quote:

Originally Posted by 96 Wideglide

Plenty of older threads on this forum 07'-09' stating Monaco used motor oil in their hyd system! Mainly models from Diplomat / H.R Endeavor, down.

Mine too. And the reasoning behind it that is if the engine driven hyd pump looses it's mechanical seal, by using engine oil, you won't contaminate the engine oil with a different type of fluid. I use engine oil in my steering and it works just fine.

RobRoy · 10-29-2017, 08:33 AM

Quote:

Originally Posted by 67fisher

Mine too. And the reasoning behind it that is if the engine driven hyd pump looses it's mechanical seal, by using engine oil, you won't contaminate the engine oil with a different type of fluid. I use engine oil in my steering and it works just fine.

Are you saying that your hyd pump is lubricated by engine oil and pressure from the engine? I have no reason to doubt you, but I'm not understanding this logic... could you please explain maybe a different way?

The hyd system on my coach operates my power steering/cooling fans and condenser fans is a totally separate system and call's for Dexron111 spec fluid and the Hyd pump used to do so is lubricated internally with that same Dexron111 from the reservoir and nothing to do with engine motor oil.