Mobiltherm 603 (5 Gal. Pail)

Mobil 100970

Mobiltherm heat transfer oils are high performance products intended for use in closed indirect heating installations. They are formulated from highly refined base stocks that are resistant to thermal cracking and chemical oxidation. They have good heat transfer efficiency and their viscosities are such that they can be pumped readily at both start-up and operating temperatures. The flash points of these oils will not decrease significantly in service because of their resistance to thermal cracking at the operating temperatures for which they are recommended. The Mobiltherm products are very thermally stable and are capable of an extremely long service life without deposit formation or viscosity increase. They demonstrate specific heats and thermal conductivities that provide more rapid heat dissipation. Mobiltherm heat transfer oils are recommended for use in both closed and open, cold-oil sealed, indirect heating and cooling systems in all kinds of industrial processes.

Product Data Sheet

Mobiltherm oils are important members of the Mobil brand of specialty fluids that have gained a reputation for performance and reliability, even in severe applications. Modern refining techniques are a key factor in providing the excellent product features.

Mobiltherm 600 Series offer the following benefits:

Features Advantages and Potential Benefits
High resistance to thermal cracking and decomposition Free from sludge and coke deposits and minimum interference with heat transfer capability and minimized maintenance needs
Excellent thermal properties High heat transfer rates and improved operating efficiency and lower operating costs
Good thermal and oxidative stability Long trouble free service life and reduced downtime
Good low temperature fluidity Easy starting of cold systems

Application Considerations: Mobiltherm heat transfer oils should not be mixed with other oils since this may impair the excellent thermal and oxidation stability resulting in a change in other properties, and complicate analyses aimed at determining useful oil life. If the oils are used above their recommended maximum temperatures, vapor lock may result unless the system is designed to operate at the higher temperature by pressurizing with an inert gas such as nitrogen. At higher temperatures, fluid life will be shortened because the rate of thermal degradation which increases markedly as temperatures rise above the recommended limit. In well-designed systems the temperature of the oil film surrounding the heating element should be about 15ºC to 30ºC above the bulk oil temperature. If higher than this, the service life of the oil may be shortened and sludge and coke may be deposited which would interfere with the heat transfer rates.

As with other mineral oils, Mobiltherm heat transfer oils should be used only in systems with forced circulation. Systems that depend on convection for circulation of the heat transfer medium do not provide a rapid enough flow to prevent local overheating and rapid deterioration of the oil. Further, these oils are not recommended for use in open systems where hot oil is exposed directly to the air. If they spray or escape from leakage points, hot Mobiltherm oils may spontaneously ignite.

Mobiltherm 600 series can be used in open and closed installations where the bulk oil temperature ranges are as outlined in the table below.

  • Mobiltherm 603: Closed Systems (-15º C to 285º C), Open Systems (-15º C7 C to 150º C)
  • Mobiltherm 605: Closed Systems (-12º C to 315º C), Open Systems (-12º C to 180º C)
  • Mobiltherm 610: Open systems (-6°C to 250°C)
  • Mobiltherm 611: Open systems (-6°C to 275°C)
Mobiltherm 600 Series 603 605 610 611
Viscosity, ASTM D 445
cSt @ 40ºC 20.2 30.4 113 490
cSt @ 100ºC 4.2 5.4 11.5 31.5
Pour Point, ºC, ASTM D 97 -15 -12 -6 -6
Flash Point, ºC, ASTM D 92 194 230 250 294
Specific Gravity @15 ºC kg/l, ASTM D 4052 0.835 0.857 0.88 0.906
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Why did you choose this?
The Lubricant Store Store
Quick and easy ordering and checkout on-line. This is a required product for our machine and most suppliers only have drums. The Lubricant Store has 5 gallon pails, good for us when we are filling machine.
Quick and easy ordering and checkout on-line. This is a required product for our machine and most suppliers only have drums. The Lubricant Store has 5 gallon pails, good for us when we are filling machine.
I needed it.
Alexander B on Aug 15, 2018
I needed it.
Alexander B on Aug 15, 2018
can i use mobiltherm 43 in place of 603?
pomaxp22 on Jun 8, 2018
BEST ANSWER: The Mobiltherm 43 is more like and comparable to the Mobiltherm 605 not the 603. The 605 is closer in performance to Mobiltherm 43 and has better low temp capabilities with the 605.
can this be used on a radiant floor heat system?
A shopper on May 10, 2018
BEST ANSWER: Potentially yes, however, we don't know how intense the heat is and we don't know if it's compatible with the piping being used. If you are needing more information please email with answers to those questions.