Hydraulic Steering Fluid

[bassburch]

Mine is low in my boat and went to bass pro and they had an oil called green marine hydraulic fluid. He says it's the same thing. I read the label and it says it works in power poles, jack plates, trim system and a few other things. Anyone know of this and can you use regular steering fluid in a hydraulic steering system.

I spent hours researching this when I needed the right fluid quickly this summer.

BOSS Snowplow Hydraulic Fluid was the only milspec 5606 available locally that wasn't priced ridiculously. I bought 2 quarts for $15. As long as you don't mind the oil being dyed red, its the same otherwise!

[QuickBullet]

Friction modifiers aren’t the same as viscosity improvers ... which are contained in DEXRON VI.
And viscosity improvers are a ‘less expensive’ way to influence the product, versus a naturally high viscosity index.
There’s a downside to viscosity improvers ... shearing. Shearing = breakdown and eventually sludge.
This is why the natural viscosity index of 5606 is designed to be 2.5X that of DEXRON VI fluids.
Such a high VI is achieved through utilizing extremely high quality base oil in the formulation of a product.

I'm well aware of what Friction modifiers and viscosity improvers do and their purpose. The friction modifiers actually come in 2 basic animals, organic and containing metal such as molybdenum dithiocarbamate. These modifiers minimize lightsurface contacts (sliding and rolling)that may occur in a given machine design and by reducing friction, improving, (or maintaining), a certain viscosity is a direct trade off....less friction = less heat = cooler oil = easy to maintain it's original vis!
I have never really counted the number of shuttle valves in an auto-trans valve body because there are hundreds of models out there however as stated earlier, they typically run in a .0015 bore clearance and are shuttled by centrifugal force, hydraulic pressure or an electric solenoid. Many rely only on a small return spring to shuttle back. Each and every time you mash the gas from a stop and get to highway speeds the average modern trans shuttles upwards of 15-20 valves and they have to be at perfect timing and sequence and have to do this no matter if the trans is -20F or 250F.
NOW, I know this has nothing to do with steering but trying to make a point, there is NO room for sludge, foreign matter or inferior oils that lack lubricity.
Sludge:
When I 1st started rebuilding automatic transmissions in 1970 about 2/3rds of everything that came in my door was so sludged up I spent more time just cleaning than rebuilding.
Through the years there was a gradual decrease in units with sludge to the point that from around 1980 to date, I can't recall 1 unit with sludge as a problem, with the exception of a few that had set for many years!

Even though friction modifiers are not really needed in a typical hydraulic steering such as Seastar, they also don't hurt anything by being there.
Viscosity improvers are in layman's terms, used to maintain a certain Vis at higher temps.....temps a steering system will never see!
Because a steering system never sees these high temps, Shearing is not in the picture!
BTW: Viscosity index of AeroShell-41 averages 214 and Mercon VI is rated at 161....this does not equal 2.5 times!
Lubricants have come a LONG way over the years, you can keep your Mineral Oil and I'll stick with the syns!
JMO

[WVBullet]

I'm well aware of what Friction modifiers and viscosity improvers do and their purpose. The friction modifiers actually come in 2 basic animals, organic and containing metal such as molybdenum dithiocarbamate. These modifiers minimize lightsurface contacts (sliding and rolling)that may occur in a given machine design and by reducing friction, improving, (or maintaining), a certain viscosity is a direct trade off....less friction = less heat = cooler oil = easy to maintain it's original vis!
I have never really counted the number of shuttle valves in an auto-trans valve body because there are hundreds of models out there however as stated earlier, they typically run in a .0015 bore clearance and are shuttled by centrifugal force, hydraulic pressure or an electric solenoid. Many rely only on a small return spring to shuttle back. Each and every time you mash the gas from a stop and get to highway speeds the average modern trans shuttles upwards of 15-20 valves and they have to be at perfect timing and sequence and have to do this no matter if the trans is -20F or 250F.
NOW, I know this has nothing to do with steering but trying to make a point, there is NO room for sludge, foreign matter or inferior oils that lack lubricity.
Sludge:
When I 1st started rebuilding automatic transmissions in 1970 about 2/3rds of everything that came in my door was so sludged up I spent more time just cleaning than rebuilding.
Through the years there was a gradual decrease in units with sludge to the point that from around 1980 to date, I can't recall 1 unit with sludge as a problem, with the exception of a few that had set for many years!

Even though friction modifiers are not really needed in a typical hydraulic steering such as Seastar, they also don't hurt anything by being there.
Viscosity improvers are in layman's terms, used to maintain a certain Vis at higher temps.....temps a steering system will never see!
Because a steering system never sees these high temps, Shearing is not in the picture!
BTW: Viscosity index of AeroShell-41 averages 214 and Mercon VI is rated at 161....this does not equal 2.5 times!
Lubricants have come a LONG way over the years, you can keep your Mineral Oil and I'll stick with the syns!
JMO

WillySteve aren’t these “Vis improvers” actually just “Vis stabilizers”? They don’t chemically change the Vis, but actually maintain or stabilize the Vis during working conditions to protect against break down. At least that’s what we use at the chemical plant where I work (been there 24 yrs). We make hundreds of different hydraulic fluids, including several flame retardant ones. Several big name companies buy from us and just stamp there name on.

[QuickBullet]

WillySteve aren’t these “Vis improvers” actually just “Vis stabilizers”? They don’t chemically change the Vis, but actually maintain or stabilize the Vis during working conditions to protect against break down. At least that’s what we use at the chemical plant where I work (been there 24 yrs). We make hundreds of different hydraulic fluids, including several flame retardant ones. Several big name companies buy from us and just stamp there name on.

Andy.....VI improvers or modifiers do chemically increase the viscosity of the fluid BUT only as its temperature rises above a configured point!
For instance a 10w-30 oil will flow like a 10w at cold temps but a 30w at high temps. The ONLY way this can be done is by chemically messing with the molecule chain of 10w oil.
At low temperatures, the molecule chain contracts and does not impact the fluid viscosity. At high temperatures, the chain relaxes and an increase in viscosity occurs.
The thing is, (or bottom line IMO), until the temp of the lubricant/fluid reaches above 40c the additives do very little if anything.

MOST boats are not operated much below 0c and seldom even see 40c. The pumps, (helm), are not constantly running for long periods of time as in a power steering unit, so they are building very little additional heat other that that of what's ambient.

[RazorCat]

Is seastar fluid that much more? Ive used maybe half a container in 10 years.

This leads to my question.
How often should you have to add fluid if there's no leaks? My boat is 11 years old in January, and I've never checked the fluid. Wouldn't know how.
Should I be adding fluid periodically, or checking it at least?

[Charles Prestridge]

This leads to my question.
How often should you have to add fluid if there's no leaks? My boat is 11 years old in January, and I've never checked the fluid. Wouldn't know how.
Should I be adding fluid periodically, or checking it at least?

You definitely should be checking at least yearly. You want to add fluid before it get too low. If it gets too low, you will have air in the system. Air will need to be purged from the system.

Even when seals are in good condition, you will have very small amounts of seepage.

Screw cap on the helm unit. Unscrew cap and look at the level. I take off the wind-screen to have better access to look at the level and add a small amount.

[QuickBullet]

You definitely should be checking at least yearly. You want to add fluid before it get too low. If it gets too low, you will have air in the system. Air will need to be purged from the system.

Even when seals are in good condition, you will have very small amounts of seepage.

Screw cap on the helm unit. Unscrew cap and look at the level. I take off the wind-screen to have better access to look at the level and add a small amount.

^^ x2 ^^ Level should be close to full

[FES313]

Needing fluid to top my system off and hearing about the astronomical prices of Sea Star fluid, to find a cheaper alternative I looked here. Then I did a search for Sea Star. Are we really arguing over $20 or less? Aeroshell 41 is about 8 bucks a quart, I found Sea Star for 19 bucks a quart. My local boat mechanic has it sitting on the shelf for $24.99. The fact a Quart will last me a really long time, The $11 difference isn't going to break the bank.

https://www.mavikmarine.com/steering...CABEgKJ5vD_BwE

[QuickBullet]

I'm not really sure opinions are classified as arguments....unless yer married!!!

[Thermodude]

I've pretty much stayed away from this one other than browsing a few of the comments.............I use Mobil Aero HF fluids, bought it in bulk!