What this product reference covers.
UTTO and STOU fluids serve combinations of transmissions, wet brakes, final drives, hydraulics and, for some products, engines under explicit equipment approvals.
Products within the family.
Names used in commerce can overlap. Use the nominated standard and exact grade rather than relying on a generic product label.
UTTO
UTTO is a recognised tractor transmission & hydraulic fluid category whose exact composition, grade limits and suitability must be confirmed from the governing specification and equipment requirement.
STOU
STOU is a recognised tractor transmission & hydraulic fluid category whose exact composition, grade limits and suitability must be confirmed from the governing specification and equipment requirement rather than inferred from the generic label.
Tractor hydraulic fluid
Tractor hydraulic fluid is a recognised tractor transmission & hydraulic fluid category whose exact composition, grade limits and suitability must be confirmed from the governing specification and equipment requirement rather than inferred from the generic label.
Synthetic multi-function fluid
Synthetic multi-function fluid is a recognised tractor transmission & hydraulic fluid category whose exact composition, grade limits and suitability must be confirmed from the governing specification and equipment requirement rather than inferred from the generic label.
What the product is built from.
| Component | Technical role |
|---|---|
| Mineral, synthetic or renewable base fluid | Provides the principal lubricating film and viscosity-temperature foundation. |
| Anti-wear / extreme-pressure system | Protects loaded contacts where the application requires it. |
| Antioxidant and corrosion inhibitors | Control ageing, deposits and surface corrosion. |
| Application-specific additives | Tune detergency, friction, demulsibility, air release, tackiness or seal compatibility. |
Define the decision before selecting the panel.
- 01
Confirm new tractor transmission & hydraulic fluid identity, grade and fitness for the intended application.
- 02
Detect contamination, degradation, mixing or storage-related change.
- 03
Investigate abnormal equipment, combustion, filtration or handling behaviour.
- 04
Establish a representative baseline for later comparison.
- 05
Support specification, maintenance and root-cause decisions with corroborated evidence.
What each result contributes.
“High” and “low” are directional investigation prompts, not pass/fail decisions. Corroborate them using the correct specification, baseline and companion evidence.
| Test / parameter | Typical methods | Why it matters | Possible causes when high | Possible causes when low |
|---|---|---|---|---|
| Kinematic viscosity | ASTM D445 / ISO 3104 | Confirms grade and detects dilution, shear, oxidation or mixing. | Oxidation, wrong oil, soot, evaporation or heavy contamination. | Shear, fuel/solvent dilution, wrong grade or lighter make-up oil. |
| Acid number | ASTM D664 | Trends acidic constituents, oxidation and contamination against a new-oil baseline. | Oxidation, overheating, acidic contamination or wrong fluid. | Fresh oil, make-up dilution or formulation difference. |
| Water | ASTM D6304 | Quantifies moisture relevant to corrosion, additive loss and film strength. | Condensation, cooler/seal leak, washdown, storage or sampling contamination. | Dry operation or dehydration; hot sampling can reduce free-water representation. |
| Elemental analysis | ASTM D5185 with PQ / ferrography where needed | Screens wear, contaminants and additive chemistry within method limitations. | Wear, corrosion, dirt, additive source, wrong oil or maintenance debris. | Stable wear, dilution, filtration or particles too large for ICP response. |
| FTIR condition | ASTM E2412 trending | Tracks oxidation and selected molecular contaminants against a comparable reference. | Heat, extended service, contamination or depleted antioxidant reserve. | Fresh oil, make-up dilution or a non-comparable baseline. |
| Friction performance | OEM-approved bench, clutch, synchroniser or wet-brake test; product specification | Confirms the controlled friction response required by transmissions, wet brakes, limited-slip axles and shared-sump equipment. | No universal high direction: excess static friction can cause chatter or harsh engagement depending on the test. | Insufficient dynamic friction can cause slip, heat and clutch wear; interpret only against the approved fluid specification. |
| Particle count / cleanliness | ISO 11500; reporting to ISO 4406 | Quantifies solid-particle cleanliness where component clearances and servo reliability are sensitive. | Dirt ingress, active wear, ineffective filtration, maintenance debris or wrong sampling point. | Effective filtration or clean new oil; settling, dilution or non-representative sampling can under-report. |
| Foaming tendency and stability | ASTM D892; ASTM D6082 where high-temperature sequence is relevant | Screens air-handling behaviour associated with reservoir foaming, compressibility, oxidation and pump or clutch performance. | Air leaks, contamination, additive depletion, overfilling, wrong oil or poor reservoir return design. | Low foam is generally favourable; antifoam overdose can impair air release even when surface foam is low. |
| Water separability / demulsibility | ASTM D1401; ISO 6614 | Assesses the oil's ability to release water in circulating, turbine, gear and hydraulic systems. | Report as persistent emulsion or longer separation time: oxidation products, incompatible mixing, detergency or contamination. | Faster separation is usually favourable but does not prove absence of dissolved or free water. |
| Wear / load-carrying performance | ASTM D4172; ASTM D2783 or application-specific gear/EP test | Characterises anti-wear or extreme-pressure performance for product qualification and comparative investigation. | For scar diameter: poor anti-wear response, contamination or depleted/additive-incompatible oil. | For scar diameter: stronger film/additive response; results do not directly predict a specific machine's wear rate. |
| Copper corrosion | ASTM D130; ISO 2160 | Screens corrosivity toward copper-containing bearings, coolers, bushings and yellow-metal components. | Reactive sulfur, acidic degradation, contamination or formulation incompatibility; report uses a corrosion rating rather than concentration. | A low corrosion rating is favourable but does not rule out in-service copper wear. |
Condition-monitoring application.
Once the product is in service, the question changes from “does it meet a product requirement?” to “what has changed, why, how confident are we and what action is proportionate?”
- 01Use a stable, representative sampling point and document operating hours, top-ups, transfers and maintenance.
- 02Trend method-consistent results rather than treating one value as a complete diagnosis.
- 03Separate new-product conformance from in-service condition and machine-wear questions.
- 04Escalate correlated evidence and rate of change; confirm surprising results before major action.