STP® Heavy Duty 50/50 Premix Antifreeze/Coolant

STP® Heavy Duty 50/50 Premix Antifreeze/Coolant is a superior fully formulated traditional engine coolant based on a proprietary formulation of corrosion inhibitors. It provides protection against radiator freeze-up down to -37°C and boil over to 129°C (with a 100 kilopascal {15 psi} radiator cap in good condition). The low silicate level of this aluminum compatible product allows it to be used in multi-vehicle fleets including automotive, light duty and heavy duty diesel applications, such as on-road truck, off-road and farm applications. It is recommended for use where a heavy duty diesel coolant is required. This includes, but is not limited to, Caterpillar, Cummins, Detroit Diesel, Ford, GM and Volvo Mack.

This product is phosphate and amine free and does not require an initial charge of supplemental coolant additives (SCA) upon initial fill. It is specially formulated to protect heavy duty diesel wet sleeve liners and is compatible with coolant filters, heavy duty diesel SCAs, hard water and other traditional fully formulated corrosion inhibited engine coolants. STP® Heavy Duty 50/50 Premix Antifreeze/Coolant provides exceptional summer cooling and excellent protection against freezing in winter while protecting all common coolant system metals.

STP® Heavy Duty 50/50 Premix Antifreeze/Coolant provides the following advantages:

  • Low silicate and phosphate free
  • Aluminum compatible
  • Protects coolant system metals such as brass, copper, solder, steel, cast iron and aluminum
  • Fully formulated; DOES NOT require initial charge of SCA
  • Premixed – DO NOT ADD WATER

STP® Heavy Duty 50/50 Premix Antifreeze/Coolant meets the performance requirements of the following specifications:

  • ASTM D3306, D4985, D6210
  • Detroit Diesel 7SE298, 93K217
  • GM 1825M, 1899
  • TMC RP 329B

Product Packaging Specifications


Unit/Case Pack




3.78 L/ 4



Typical Product Properties

Characteristic Performance Test Method
pH 10 – 11 ASTM D1287
Specific gravityb 1.070 – 1.090 ASTM D1122
Freeze point, °C/°F -37/-34 ASTM D1177
Foam volume, ml 150 max. ASTM D1881
Foam break time, second 5 max. ASTM D1881
Reserve Alkalinity, ml 5.0 min. ASTM D1121
Chloride, ppm 25 max. ASTM D3634
Silicon, ppm 125 max. ASTM D6130
Colour Purple  
Glycol Content, % wgt. 46 min.  
Inhibitors & Water Content, % wgt. 54 max.  

b Measured at 15.6ºC/60ºF

Typical Coolant Performance Testing Results

Test Results¹ Max. Spec. Test Results¹ Max. Spec.
Copper 1 10 -1 20
Solder 4 30 14 60
Brass 1 10 2 20
Steel 1 10 0 20
Cast Iron -5 10 -6 20
Aluminum -2 30 1 60

1 Weight loss, except negative sign which indicate weight gain, per coupon in milligrams. Values are for coolant made from virgin ethylene glycol.

  Test Results¹ Specification
ASTM D4340 Heat Rejecting Aluminum Corrosion (mg/cm²/week) 0.2 1.0 maximum
ASTM D2809 Aluminum Water Pump Cavitation- Erosion Corrosion Rating 8 8 minimum

1 Weight loss per coupon in milligrams (average for 2 tests). Values are for coolant made from virgin ethylene glycol.

NOTICE: This product is shipped in compliance with applicable laws and regulations regarding classification, packaging, shipping and handling. The performance and physical property data described for this product are typical results not sale specifications, except where maximum or minimum is indicated. Refer to Material Safety Data Sheets for further information. Because use conditions and applicable laws may differ from one location to another and may change with time, the customer is responsible for determining whether product and the information in this document are appropriate for their use and for ensuring that their workplace and disposal practices are in compliance with applicable laws and other governmental enactments. Recochem’s warranty is limited to the claims of product meeting stated performance specifications. It is the responsibility of the end-user to determine product suitability as recommended in the owner’s manual and to follow engine manufacturer’s instructions.