Frequently Asked Questions
  • DEF is a proven technology worldwide.
  • It is extremely essential that all vehicles on the Indian roads are compliant with the BS4 emission norms.
  • If your vehicle is fitted with SCR technology, you will have to use DEF for the vehicle to run.
  • DEF is a combination of Technical Grade Urea and Deionized water in the ration 32.5% to 67.5%
  • It is manufactured as per ISO 22241 and IS 17042.
  • Highly quality sensitive product that can damage the SCR system if in degraded condition.


Colourless clear liquid

Incipient Crystallization

-11.5 °C

Viscosity (@25°C)

Approx. 1.4 mPa.s

Thermal Conductivity (@25°C)

Approx. 0.570 W/m.K

Specific Heat (@25°C)

Approx. 3.4 kJ/kg.K

Specific Tension (@20°C)

Min. 65 mN/m

Source: ISO 22241-1:2006(E)

  • Diesel Engines fitted with SCR Technology having a designated DEF tank use DEF to reduce NOx emissions.
  • When DEF is sprayed on the hot exhaust gas, the water evaporates and urea undergoes thermal decomposition to form Ammonia and Carbon Di Oxide
  • Ammonia in the presence of Oxygen and a catalyst reduces NOx to Nitrogen with Water Vapor and Carbon Di Oxide as by products.
  • Vehicle engines run with a “Lean Burn” Principle. Excess air is used with the fuel to ensure fuel and soot is fully burned, increasing engine performance, fuel economy and NOx emissions.
  • DEF is used as an after treatment to the lean burn principle to reduce NOx emissions to the desired levels as stated in BS 4 emission norms.
  • Hence DEF does not directly enhance engine performance or fuel economy but does so indirectly.
  • DEF is used to satisfy emission norms which are legally binding on all stakeholders.
  • Hence OEMs have checks in place to ensure the vehicle does not run without DEF.
  • Some vehicles do not start without DEF while other vehicles do not have torque. It will be impossible to run the vehicle at optimum performance without refilling the DEF tank.
  • Quantity of DEF required depends upon the engine operating temperature and speed
  • Long workings hours will increase the engine temperature and hence the usage of DEF as compared to short working hours
  • Typically the usage of DEF is 2-6% of diesel consumption, if you use 100L of diesel then you will need 2-6L of DEF

DEF is available in 20L cans/buckets, 210L barrels, 1000L IBC Tanks 20,000 – 30,000L SS Tankers

  • DEF is a temperature sensitive liquid
  • The ideal storage temperature for DEF is 25 °C and maximum storage temperature is 30 °C (as per ISO 22241 Part 3).
  • Recommended material for storage and dispensing of DEF are Plastic or Stainless Steel


Once Seal is broken, consume DEF completely. 

Do not leave container open at any time.  

tends to evaporate and crystalize when exposed to the atmosphere in Indian temperatures. 

An open container can also attract dust and insects from the atmosphere. 


Keep DEF away from direct sunlight.  

Ensure the product is not exposed to prolonged periods of high temperature.

 Shelf life of DEF reduces with increasing temperature. 


Always consume the old stock first and then consume the new stock 

Do not use DEF that has crossed 6 months from the date of manufacturing 

Optimum temperature for shelf life of 6 months is 30 Degree Celsius, which is the normal room temperature in India. 


Use only Plastic or stainless steel while handling DEF. Always wash such instruments with De-Ionized Water and DEF before use.

Do not use dirty containers or pumps while handling DEF. 

 Contaminated DEF will result in a shorter lifespan of the SCR catalyst, pumps and nozzles.


Ensure instruments used with DEF are not used for any other products.

Do not wash instruments with Tap water as it contains. 

Tap water has high salts and minerals which will affect the quality of DEF. 


  • No, DEF works only with SCR Technology
  • OEMs will provide a designated DEF tank in which only DEF is to be added.
  • DEF is not supposed to be mixed with diesel, there will be a designated tank for DEF. It is not a diesel additive.
  • DEF is used to reduce NOx emissions to meet BS4 emission norms
  • Petrol engines emit more Carbon Monoxide than NOx
  • Hence petrol engines already satisfy NOx emission standards even without the use of DEF
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