Difficulty starting a low-temperature system: Can IOTA-2056 PES directly replace methyl silicone oil｜IOTA

You cannot directly replace methyl silicone oil in low-temperature hydraulic or damping systems simply because IOTA-2056 PES has a pour point below −70°C. First, verify the full specifications of the currently used fluid, its viscosity at room and low temperatures, the equipment's minimum startup temperature, load, clearances, seal materials, and operating temperature range; then, compare PES-1 and PES-2 with the current fluid.IOTA-2056 PES产品资料 

IOTA-2056 PES is a polyethylsiloxane fluid. Public data from IOTA lists it for use in hydraulic systems, instrument lubrication, and as a low-temperature oil base, with an operating temperature range of −70°C to 150°C. It is a candidate material for applications requiring low-temperature fluidity or compatibility with mineral oil systems; however, whether it actually improves startup, damping, or lubrication performance must be verified in the actual equipment.

Why does a pour point below −70°C not guarantee that the equipment can start?

The pour point primarily indicates the temperature range at which a fluid loses its fluidity under specified test conditions. Whether equipment can start at low temperatures also depends on the following factors:

Actual viscosity at the minimum temperature.

Design of pumps, valves, bearings, or damping mechanisms.

Component clearances and oil film thickness requirements.

Startup load and drive power.

Duration of exposure to low temperatures.

Shrinkage and hardening of seal materials.

Existing fluids, additives, and contaminants in the system.

Difference between ambient temperature and internal oil temperature.

Therefore, a "pour point below −70°C" serves as a criterion for screening candidate materials; it does not equate to a guarantee that the equipment will start at −70°C.

What are the published specifications for IOTA-2056 PES?

Parameter	IOTA-2056 PES-1	IOTA-2056 PES-2
Appearance	Colorless to pale yellow liquid	Colorless to pale yellow liquid
Viscosity at 25°C	34–40 mm²/s	180–280 mm²/s
Refractive index	1.44	1.44
Flash point	>170°C	>265°C
Density at 20°C	0.95–0.98 g/cm³	0.99–1.02 g/cm³
Pour point	<−70°C	<−70°C
Acid value	<0.1 mg KOH/g	<0.1 mg KOH/g
Published operating temperature range	−70 to 150°C	−70 to 150°C

 

The data above is based on IOTA's currently published product information. Formal procurement and batch acceptance should be based on the valid TDS, specifications, and batch COA confirmed by both parties. IOTA-2056 PES产品资料 

How should one choose between PES-1 and PES-2?

Selection should not be based solely on the minimum temperature, as both grades share the same published pour point, yet there are significant differences in room-temperature viscosity and flash point.

Operating conditions	PES-1 candidate direction	PES-2 candidate direction	Verification required
Priority on ultra-low temperature startup	Lower viscosity at room temperature facilitates initial screening for low-temperature flow	Need to verify if low-temperature resistance is excessive	Viscosity at minimum temperature, startup current, and response time
Precision instrument lubrication	Flowability and low-temperature response can be evaluated	Requirement for a thicker oil film can be evaluated	Clearance, load, wear, and migration
Damping mechanism	May provide lower damping levels	May provide higher damping levels	Damping curve across the full temperature range and response consistency
Hydraulic transmission	Initial screening for low-temperature pumpability can be performed	Assessment must consider pump type and load	Pump efficiency, leakage, cavitation, and sealing
Continued operation required after temperature rise	Flash point data should be included in the evaluation	High published flash point	Actual temperature, atmosphere, volatility, and service life
Blending with other base oils	Mixing ratios can be varied	Mixing ratios can be varied	Miscibility, viscosity, sedimentation, and long-term storage

 

Lower viscosity does not imply suitability for all low-temperature equipment; higher viscosity does not necessarily guarantee superior overall lubrication performance. The final choice depends on pumpability, clearance, load, and damping requirements.

What are the key differences in selection criteria between IOTA-2056 PES and methyl silicone oil?

Comparison criteria	IOTA-2056 PES ethyl silicone oil	Conventional methyl silicone oil	Selection parameters
Low-temperature performance	Suitable candidate for ultra-low-temperature fluidity applications	Depends on specific viscosity grade and product structure	Actual viscosity at the target temperature must be compared
Oil blend systems	Public data lists compatibility with mineral oils and synthetic oils	Compatibility depends on the specific oil and formulation	Miscibility does not equate to long-term formulation stability
Lubrication and damping	Suitable for instrument lubrication, hydraulics, and low-temperature oil bases	Widely used for damping, lubrication, and insulation applications	Testing based on the specific friction pair and damping requirements is necessary
Continuous high-temperature operation	Published upper operating limit is 150°C	Some methyl silicone oils can be used in higher-temperature applications	Assessment should be based on specific grade, atmosphere, and service life
Substitution methods	Cannot substitute directly based solely on name or room-temperature viscosity	Full grade specifications of the currently used product must be confirmed	Validation of cleaning, mixing, or residue management strategies is required

 

Ethyl silicone oil and methyl silicone oil are better suited to complement each other based on operating conditions, rather than one being described as a universal upgrade or substitute for the other across all temperature ranges.

Why is full formulation testing still required despite miscibility with mineral oil?

IOTA's public data lists compatibility with mineral and synthetic oils as a feature of IOTA-2056 PES; however, actual systems may also contain:

Anti-wear agents.

Antioxidants.

Rust inhibitors.

Viscosity index improvers.

Antifoaming agents.

Sealing materials and hoses.

Aged oil and deposits from the original system.

Moisture, particulates, or cleaning residues.

A uniform appearance or lack of phase separation in the base oil over the short term does not guarantee stability after low-temperature storage, thermal cycling, shearing, or long-term operation. Verification using the complete formulation and actual materials should be conducted prior to substitution.

What parameters should be confirmed for low-temperature hydraulic systems?

Operating condition category	Information requiring confirmation
Minimum ambient temperature	Minimum temperature for equipment storage and operation
Minimum oil temperature	Actual temperature of internal system fluid at startup
Continuous temperature	Normal stable operating range
Peak temperature	Maximum value, duration, and frequency of occurrence
Duration of low-temperature exposure	Cold soak for hours, days, or longer
Pump and valve construction	Pump type, valve orifices, clearances, and allowable viscosity range
Startup requirements	No-load or loaded startup, starting current, and allowable response time
Pressure and flow rate	Operating pressure, peak pressure, and target flow rate
Currently used oil	Full name, viscosity grade, additives, and service duration
Sealing materials	Rubber, plastics, coatings, hoses, and bonding materials
Cleanliness	Moisture, particulates, old oil, and cleaning agent residues
Acceptance criteria	Startup, pressure, flow rate, leakage, wear, and service life

 

Specifying only a "minimum temperature of -60°C" is insufficient for selecting PES-1 or PES-2.

What aspects of the damping mechanism should be prioritized for verification?

Damping force or response time within the target temperature range.

Initial operation after low-temperature cold soak.

Damping stability after multiple cycles.

Damping decay following a rise in temperature.

Shaft, piston, orifices, and mating clearances.

Low-temperature shrinkage and friction changes in seals.

Fluid migration, leakage, and volatilization.

Vibration frequency, displacement velocity, and load.

Start-up consistency after prolonged static storage.

Comparing viscosity at 25°C alone cannot predict full damping performance across the range from -60°C to normal operating temperatures.

How should tests be designed when replacing the currently used methyl silicone oil?

1. Establish a baseline for the current oil

Record the full model, batch number, service duration, contamination status, and failure characteristics of the oil currently in use. Do not use aged or contaminated used oil directly as the performance baseline for new oil.

2. Standardize test conditions

Item	Standardized requirement
Sample condition	New oil vs. new oil; or record the condition of used oil separately
Sample quantity	Keep consistent
Low temperature	Match the equipment's minimum oil temperature
Cold soak duration	Sufficient for sample and equipment to reach thermal equilibrium
Load	Keep identical
Measurement method	Consistent methods for viscosity, torque, pressure, flow rate, and response
Equipment status	Unchanged pump, valve, seal, clearance, and control parameters

 

3. Select candidate samples

Fresh sample of the currently used methyl silicone oil.

IOTA-2056 PES-1.

IOTA-2056 PES-2.

To evaluate the effects of mixing residues, include a test group with a known mixing ratio.

Do not perform direct mixing in production equipment without a recorded, known ratio.

4. Complete testing across the full temperature range

Initial state at 25°C.

Cold soak at the specified minimum temperature.

Start-up at the minimum temperature.

Temperature ramp-up process.

Normal operating temperature.

Peak temperature.

Multiple thermal cycles (hot/cold).

5. Evaluate actual results

Record starting current, pressure build-up time, flow rate, damping force, torque, leakage, noise, wear, and changes in oil appearance and viscosity. A decision to proceed with formal replacement should be made only after both equipment performance metrics and material conditions meet requirements.

Under what circumstances is the direct use of IOTA-2056 PES unsuitable?

Long-term operating temperatures approach or exceed the published upper application limit.

The equipment manufacturer mandates the use of specific oils or certified fluids.

The composition of additives and seal materials in the current system is unknown.

Specific approvals (e.g., flame retardancy, food contact, aerospace, or other industry standards) are required but relevant documentation has not yet been obtained.

There are specific requirements regarding vapor pressure, volatility, outgassing, or ultra-high vacuum performance.

Only ambient temperature is known; data on minimum oil temperature, low-temperature viscosity, and start-up load is missing.

The customer requests direct mixing with in-use methyl silicone oil but cannot control the residual ratio.

In these cases, additional information or specialized validation is required; decisions cannot be based solely on the product name.

What selection support can IOTA provide?

As a "solution provider for the entire silicone industry chain," Anhui Iota Silicone Oil Co., Ltd. can assist in comparing low-temperature flow, room-temperature viscosity, flash point, mixed oil systems, and equipment operating conditions regarding IOTA-2056 PES-1 and PES-2.

For hydraulic, damping, or instrument lubrication projects requiring both low-temperature startup and elevated-temperature operation, the following information should be provided prior to product selection:

Minimum oil temperature and continuous operating temperature.

Structure of the pump, valve, or damping mechanism.

Complete model number of the oil currently in use.

Target viscosity or damping range.

Seal and adjacent materials.

Operating pressure, load, and cycle frequency.

Failure characteristics and acceptance criteria.

Only after receiving complete information can a determination be made on whether to prioritize testing PES-1 or PES-2, or to continue using the corresponding methyl silicone oil approach.

Common Misconceptions

1. If the pour point is below −70°C, the equipment can start normally at −70°C.

Pour point is not equivalent to the equipment's minimum startup temperature. Low-temperature viscosity, load, drive power, and structural resistance are equally important.

2. PES-1 has lower viscosity, so it must be more suitable for all low-temperature equipment.

Lower viscosity may benefit low-temperature flow but can also affect oil film integrity, leakage, damping, and load-bearing capacity; equipment-specific validation is required.

3. PES-2 has a higher flash point, so its overall performance must be superior.

Flash point is merely one selection criterion; it cannot replace evaluations of low-temperature viscosity, lubrication, damping, and actual equipment response.

4. Compatibility with mineral oil means it can be added directly to a system currently in use.

Factors such as additives, seal materials, contamination from old oil, mixing ratios, and long-term stability still need to be verified.

5. If viscosities at 25°C are identical, they can be substituted on an equal-quantity basis.

Fluids with different chemical structures may exhibit differences in viscosity-temperature relationships, lubrication characteristics, compatibility, and volatility.

6. Ethyl silicone oil outperforms methyl silicone oil at all temperatures.

The two types of fluids offer different advantages. Ethyl silicone oil is suitable for applications prioritizing low-temperature performance and mixed-oil systems, whereas certain long-term high-temperature operating conditions may be better suited to specific methyl silicone oils or other silicone oil chemistries.

Recommended Selection Steps

Determine the minimum ambient temperature and the minimum internal oil temperature of the equipment.

Record continuous operating temperatures, peak temperatures, and their respective durations.

Identify the exact model and viscosity grade of the methyl silicone oil currently in use.

Check pump specifications, valves, clearances, loads, and startup power requirements.

Check compatibility with seals, hoses, plastics, and coating materials.

Make a preliminary selection of PES-1 or PES-2 based on requirements for low-temperature flow, oil film formation, and damping.

Compare the relevant Technical Data Sheet (TDS) with the Certificate of Analysis (COA) for the specific delivery batch.

Conduct bench tests covering low-temperature cold soaking, startup, and the full operating temperature range.

Verify compatibility with the complete additive package and sealing system.

Finalize the replacement plan only after completing multiple thermal cycling tests and verifying multiple product batches.

FAQ

Can IOTA-2056 PES directly replace DC 200 or other methyl silicone oils?

Direct replacement based solely on the silicone oil category is not appropriate. Specific viscosity grades, minimum oil temperatures, continuous high-temperature exposure, equipment loads, seal materials, and complete formulations must be compared.

Does the fact that IOTA-2056 PES has a pour point below −70°C mean its viscosity remains low at −70°C?

That is not the correct interpretation. The pour point indicates flow characteristics only under specified conditions; actual viscosity and equipment response near −70°C require testing.

Which is more suitable for startup at −60°C: PES-1 or PES-2?

PES-1 has lower viscosity at 25°C and is a primary candidate for low-temperature flow applications; however, the final choice depends on pump type, load, oil film requirements, leakage considerations, and damping needs.

PES-2 has a higher flash point than PES-1; is it more suitable for high-temperature operation?

A higher flash point is a reference factor but cannot solely determine service life at high temperatures. Factors such as actual operating temperature, atmosphere, volatility, oxidation, and viscosity changes must also be evaluated.

Can IOTA-2056 PES be mixed directly with mineral oil?

Published data indicates compatibility with mineral and synthetic oils; however, specific base oils, additives, mixing ratios, and long-term thermal cycling performance still require verification.

Is it necessary to thoroughly clean the system before switching to ethyl silicone oil?

There is no single answer. The decision depends on the current oil, contamination status, equipment manual, residual oil ratio, and the purpose of the verification. When establishing a formal replacement protocol, controlled draining and flushing usually facilitate a clearer assessment of the results.

Is a low-temperature beaker flow test sufficient?

No, it is not sufficient. Beaker tests cannot simulate pumping, valve response, damping force, seal friction, or cold-start under load; bench testing or actual equipment testing should be included.

Products related to this article

IOTA-2056 PES Ethyl Silicone Oil

A polyethylsiloxane fluid suitable for low-temperature hydraulics, damping, instrument lubrication, and low-temperature oil-based applications. Available grades include PES-1 and PES-2 (differentiated by viscosity); selection should consider minimum oil temperature, load, oil film characteristics, damping requirements, and heat-up operating conditions. IOTA-2056 PES产品资料 

PES-1 (Low-viscosity grade)

Published viscosity at 25°C is 34–40 mm²/s; suitable for initial screening regarding low-temperature flow and start-up response, though equipment leakage, oil film integrity, and load-bearing requirements still require verification.

PES-2 (Higher Viscosity Variant)

The kinematic viscosity at 25°C ranges from 180 to 280 mm²/s; it is suitable for evaluation in applications requiring specific damping characteristics or oil film conditions. Suitability cannot be determined solely based on its higher flash point.