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D4985-10 – Standard Test Method Technical Guide
📜 Scope and Key Specifications
This standard specifies requirements for low silicate ethylene glycol base engine coolants designed for heavy-duty engines, particularly those with wet cylinder liner-in-block designs and similar systems requiring a pre-charge of Supplemental Coolant Additive (SCA). The coolant concentrates must be used at 40 % to 60 % concentration by volume in water, or prediluted glycol base coolants with a minimum 50 volume % glycol may be used without further dilution. In either form, the coolant provides protection against corrosion, freezing to at least −36.4 °C (−33.5 °F), and boiling to at least 108 °C (226 °F).
This specification is based on new or virgin ingredients; for coolants prepared from recycled or reprocessed materials, refer to Specification D6210. The standard mandates an initial charge of SCA and regular maintenance doses, with the responsibility for defining SCA addition practices placed on the engine or vehicle manufacturer. If no instructions are provided, follow the SCA supplier’s recommendations.
🧪 Key Test Methods and Performance Criteria
Conformance to D4985‑10 is verified through a suite of ASTM test methods that assess chemical composition, physical properties, and corrosion inhibition performance. The following referenced test methods are critical for evaluating coolant quality and compliance:
| 🟦 Test Method | 📐 Description | 🎯 Key Requirement |
|---|---|---|
| D1120 | Boiling Point of Engine Coolants | Minimum 108 °C (226 °F) at use concentration |
| D1177 | Freezing Point of Aqueous Engine Coolants | At least −36.4 °C (−33.5 °F) |
| D1121 | Reserve Alkalinity of Engine Coolants | Ensures adequate buffer capacity for pH stability |
| D1384 | Corrosion Test for Engine Coolants in Glassware | Acceptable metal weight loss limits per D15 standards |
| D2570 | Simulated Service Corrosion Testing of Engine Coolants | Validates long‑term corrosion protection |
| D2809 | Cavitation Corrosion of Aluminum Pumps | No excessive pitting or erosion under pump conditions |
Additional tests for chloride ion (D512), sulfate ion (D516), ash content (D1119), water content (D1123), pH (D1287), and foaming tendencies (D1881) help ensure the coolant meets chemical purity and performance specifications for heavy‑duty service.
🛡️ SCA Maintenance and Usage Requirements
Coolants meeting this standard are not standalone long‑life coolants; they require a pre‑charge of Supplemental Coolant Additive (SCA) before service and regular maintenance doses to sustain protection against liner pitting, scale, and corrosion. The SCA must be compatible with the coolant formulation. Users must follow engine manufacturer or SCA supplier instructions for dosage frequency and concentration, as over‑ or under‑charging can affect cooling system performance.
⚠️ Important Technical Note: This standard applies exclusively to coolants intended for heavy‑duty engines that mandate SCA pre‑charge. Do not use this coolant in lightweight vehicle cooling systems unless specifically indicated by the manufacturer. Always verify that the SCA used is compatible with the specific ethylene glycol base coolant formulation and with other cooling system materials (e.g., aluminum, cast iron, rubber gaskets). The specified freezing and boiling points apply only when the coolant is used at the correct concentration range.
💡 Best Practice: Maintain the coolant concentration between 40 % and 60 % glycol by volume to ensure both frost protection and heat transfer efficiency. For prediluted products, do not add water. Regular SCA maintenance should be scheduled based on engine hours or mileage, and coolant condition should be monitored by testing reserve alkalinity and SCA level at each interval.
❓ Frequently Asked Questions
🔍 What is the main function of SCA in this standard?
Supplemental Coolant Additive (SCA) prevents cavitation corrosion and erosion‑corrosion on wet cylinder liners, controls scale formation, and maintains proper pH. The pre‑charge and maintenance doses ensure continuous protection throughout the coolant’s service life.
💡 What coolant concentration should be used with this standard?
For concentrated coolants, mix with water to achieve 40 % to 60 % glycol by volume. Prediluted coolants (minimum 50 % glycol) are used as‑is without further dilution. This range ensures a freezing point down to −36.4 °C (−33.5 °F) and a boiling point of at least 108 °C (226 °F).
⚡ How does D4985‑10 differ from D6210?
D4985‑10 is intended for coolants made from new or virgin ingredients and requires SCA pre‑charge and maintenance. D6210 covers heavy‑duty engine coolants that may be produced from recycled or reprocessed used coolant or industrial‑source ethylene glycol, and it does not mandate SCA pre‑charge if the coolant is formulated as a fully formulated product meeting that standard.
📌 Can this coolant be used in light‑duty vehicles?
It is primarily designed for heavy‑duty engines requiring SCA pre‑charge, such as those with wet cylinder liners. Use in light‑duty vehicles is not recommended unless explicitly approved by the vehicle manufacturer, as SCA over‑treatment may cause issues with modern aluminum cooling systems and silicate gel formation.