Mercury Quicksilver Power Steering Fluid 858078Q01
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Mercury Quicksilver 858078Q01 is genuine OEM Hydraulic Helm Steering Fluid supplied in a 32 oz bottle for compatible non-power hydraulic steering systems. It is formulated for marine hydraulic helm systems where the steering fluid must provide proper lubrication, smooth steering response, and long steering-system service life. This is the correct Mercury / Quicksilver fluid for applications that specify hydraulic helm steering fluid, not a general power trim fluid or electric power steering fluid.
Key Features
- Genuine Mercury Marine / Quicksilver OEM steering fluid.
- Part number 858078Q01.
- Full OEM-style reference: 92-858078Q01.
- Supplied in a 32 oz / 1 quart bottle.
- Designed for non-power hydraulic steering systems.
- Suitable for MerCruiser compact hydraulic helm steering systems where specified.
- Suitable for compatible bolt-on hydraulic steering systems, including SeaStar-style helm systems where this fluid specification is required.
- Meets MIL Spec H5606G.
- Helps support smooth hydraulic steering operation.
- Produced to Mercury Marine OEM specifications for Mercury, Mariner, and MerCruiser marine applications.
- Not intended for non-compatible electric power steering systems or other systems requiring a different Mercury / Quicksilver steering or trim fluid.
Application Compatibility
This is not an engine-specific product. It is selected by the boat’s hydraulic steering system requirements and the fluid specification listed in the owner’s manual or service manual.
Commonly used for:
- Non-power hydraulic helm steering systems
- MerCruiser compact hydraulic helm steering systems
- Compatible bolt-on hydraulic steering systems
- Mercury, Mariner, and MerCruiser marine steering applications where 858078Q01 / 92-858078Q01 or hydraulic helm steering fluid is specified
Do not select this fluid by engine model alone. The correct match is the steering system and fluid requirement.
Fitment & System Compatibility Notice
Confirm the correct steering-fluid requirement in the boat’s owner’s manual, service manual, or helm steering system documentation before use. Hydraulic helm steering fluid, power trim and steering fluid, and synthetic electric power steering fluid are not always interchangeable, even though the containers and descriptions can sound similar.
When This Product Needs Replacement
Use this fluid when topping off, bleeding, flushing, or servicing a compatible hydraulic helm steering system. Steering fluid should be checked when steering becomes noisy, inconsistent, spongy, hard to turn, or after any steering component has been replaced, disconnected, or serviced.
Installation Notes
Use clean filling and bleeding equipment to avoid introducing dirt, water, or air into the steering system. Follow the steering-system manufacturer’s bleeding procedure, keep the reservoir filled during service, and do not mix with unknown or incompatible fluids. If old fluid is contaminated, discolored, or aerated, the system should be inspected before refilling.
Alternate/Superseded Part Numbers
Active and related OEM references include:
- 858078Q01
- 92-858078Q01
Related earlier reference commonly associated with this fluid:
- 862014Q1
Parts Desk Insight
The important detail with this bottle is that it is hydraulic helm steering fluid for non-power hydraulic steering systems. It should not be confused with Mercury power trim fluid or synthetic electric power steering fluid, so checking the steering-system requirement first prevents the wrong fluid from being added.
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.