Selecting Hoses for Different OAT Coolants

Selecting Hoses for Different OAT Coolants

Selecting hoses for different Organic Acid Technology (OAT) coolants is a daunting task. With several hose options available today, choosing the right hose that meets your needs is difficult. So, where do you start? Here’s what you need to know about OAT Coolants and how to choose the correct hose!

What is OAT Coolant?

OAT is an acronym for Organic Acid (Additive) Technology which describes the type of materials responsible for the corrosion protection offered by a coolant of this type. OATs are Long Life/Extended Life Coolants, based on minimally depleting Carboxylate Technology. This technology provides superior protection to all components of the cooling system including materials like aluminum and magnesium found in the modern-day engine. Unlike Traditional Coolants the need for regular additions of Supplemental Coolant Additives (SCA’s) at scheduled service intervals is no longer required, providing a true Long-Life product which can provide significant “cost savings”. In some heavy-duty diesel applications, you may see a reference to a Coolant Extender. A Coolant Extender can be used with an OAT coolant to top-up certain additives at the products half-life which is typically around 480,000 kms. In general OAT based corrosion inhibitors are recognized for their non-toxic properties making them readily biodegradable, addressing any environmental and occupational health & safety issues.

Characteristics of OAT Coolant

  • Corrosion Inhibitors based on fully neutralized organic acids and azoles
  • Typically, amber, orange or red in color
  • Designed for use in automotive, light duty and heavy-duty diesel applications
  • Silicate free, avoids silicate gelation and related fallout issues
  • Amine, borate, nitrite and silicate free meeting the basic chemistry requirements of Asian OEM’s
  • Phosphate free, meeting some basic chemistry requirements of European and some North American OEM’s
  • Excellent high temperature aluminum protection
  • Can provide wet sleeve liner cavitation protection without the use of nitrite
  • Extended life in both light and heavy-duty applications
  • Lifespan: Automotive – Up to 5 years or 250,000 km (150,000 miles); Heavy Duty – Up to 6 years or 960,000 km (600,000 miles)


How to choose the correct hose depending on the coolant and other working conditions

Please see the below flowchart/ready-reckoner, to choose the correct hose depending on the coolant and other working conditions. Silicone Hoses might not work for some OAT or hybrid-OAT coolants, even if EHAs are absent. Using the wrong hoses can lead to coolant losses (sweating), and damage to the fabric reinforcement layer, causing pre-mature hose failures.


Organic Acid Based Coolants which contain Ethlyhexanoic acids, are incompatible with Silicone Hoses. EHA/EHA acids gradually soften the silicone hoses (even if they are lined with Fluorosilicone) and cause them to ultimately burst.

Hoses for ‘Organic-Acid-Technology’ Coolants

We offer a special range of hoses, for resistance to organic acid-based coolants, which contain sebacate or 2-ethylhexanoic acid. Hybrid (HOAT) coolants are generally moderately ‘silicated’ for improved aluminium protection.

However, these extended life anti-freeze coolants which are extremely corrosive in nature, require hoses of specially designed materials. Using normal blue coolant hoses of the standard material for these coolants, will result in pre-mature failures.

Shore Auto offers the below Hoses Organic Acid TechnologyCoolants.

Shore BOLT:

4-ply reinforced Silicone. The ‘special’ reinforcement is capable of withstanding the gases which permeate the silicone liner and can damage the ‘polyester’ fabrics. Hence, the liner and the fabric are designed to withstand these gases for extended periods. Typical temperature range: -50 to + 215 degrees Celsius.



A special grade of EPDM reinforced with 1-ply Aramid. This option can only withstand -40 to + 150 degrees Celsius; however, it scores over the Shore-Master, when it comes to resistance to potassium/sodium 2-ethylhexanoic acids, which are sometimes present in OAT coolants.

Shore BOLT+:

The Shore Bolt+ is designed with an impermeable inner liner, which can give the hose an even longer life than the Shore BOLT, as the gases that can permeate the ‘silicone’ liner, cannot permeate this special ‘inner’ liner. The common mis-conception in the market is that an inner liner of Fluorosilicone adds to the protection. However, as per our testing, potassium/sodium 2-ethylhexanoic acids deplete the Fluorosilicone liner also very quickly. Our ‘special’ inner liner, hence, has been designed to withstand the harshest of chemicals/gases. Typical temperature range: -25 to + 225 degrees Celsius.


All sizes in straights, straight reducers, elbow 90-degree, elbow 45-degree, elbow 135 degree and 180 degrees are available. We will also be glad to develop bespoke shapes as per your requirement/design. Below is the Pressure Rating for the Shore BOLT.

 Burst Pressure for SHORE BOLT and SHORE BOLT+

ID (mm) Burst Pressure (bar) ID (mm) Burst Pressure (bar)
14 37.4 34.0 17.5
18 32.6 42.0 14.3
21 27.5 45.0 13.4
24 22.8 50.0 12.4
27 21.4 51.0 10.9


Still need help on selecting the hoses for different Organic Acid Technology (OAT) coolants? We will be happy to help you in your evaluation process: Contact Us