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Tannas Co. & King Refrigeration, Inc. Precision Laboratory Instruments for Routine Testing and Advanced Research & Development of Engine Oils, Lubricants, and Related Fluids


Thermo-oxidation Engine Oil Simulation Test

Test Methods

ASTM D6335   |   Dual/33C Model  (Chinese SH/T0750)
ASTM D7097   |   MHT Model (Moderately High Temperature)

Models Available





The TEOST 33C test simulates the effect of engine operating conditions on the oxidation and deposit-forming tendencies of engine oils, especially in the high temperature Turbocharger area. The TEOST MHT™ test simulates similar effects and conditions found in the ring belt and piston ring areas of the engine.

Oil samples treated with catalysts are pumped over a heated 33C Depositor Rod or a coiled MHT Depositor Rod on which deposits form. The weight of the Depositor Rod after the test is subtracted from its pre-test weight and added to the particulate weight collected by filtering the oil remaining. The results are reported in milligrams.

Features & Benefits

  • Adjustable temperature zones and pump speeds.
  • Clear Glass Mantle for easy viewing of depositor area during test.
  • Ability to collect the volatilized material for further analysis and investigation.

Reference Oils & Catalysts

33C Reference Oils | ASTM D6335 MHT Oils & Catalyst | ASTM D7097 TEOST™ Calibration Oil
T33C-1 MDF
MHT Catalyst

For a complete listing of part numbers and available container sizes of TEOST™ Reference Oils & Catalysts, please review the Tannas Reference Oils & Catalysts Parts List.

Visit our Certified Reference Materials page to download SDS sheets or Oil Certificates.

Parts & Accessories

Depositor Rods:
500012:  TEOST™ 33C Depositor Rods (10 rods/box)
500993:  TEOST MHT™ Depositor Rods (10 rods/box)
Optional Accessories:
500990:  33C/Dual Mass Flow Controller
500995:  MHT™ Mass Flow Controller
500075:  Thermocouple Depth Gauge
500070:  Two-Channel Chart Recorder - R
500065:  Chart Recorder Paper - R
500024:  Chart Recorder Pen - Black
500067:  Chart Recorder Pen - Red
Spare Parts & Consumables (for either Test):
500030:  TEOST Filter Cartridges w/Caps
500612:  T/C Main (J-type)
500614:  T/C Over-Temp. (K-type)
500409:  Depositor Rod O-Rings (20/pack)
500892:  Filtering Flask Funnel
500856:  Filter Tube Assembly
500016:  Steel Wool
500019:  Pipe Cleaners (100/box)
500084:  Disposable Pipette
500428:  #8 Rubber Stopper
300995:  Combination Wrench 7/16
500872:  Thermocouple Collar Assembly
020044:  TPC Calibration Oil (0.47 L | pint)
200103:  Syringe (100 microliter)
500076:  Weighing Boats
300815:  Tool Box
500822:  Spare Fuse Set (for either 110V or 220V)
500085:  Plastic Depositor Rod Holder
500715:  Protective Shield
Allen Keys for cabinet (P/Ns 500610, 500611, 500613)
Contact Tannas for additional spare parts, reference oils, and accessories to run the MHT and 33C tests.


TEOST Rods with description.JPG

Depositor Rods crafted from precision machined steel meet Tannas specifications for exclusive use in TEOST™ tests.  All rods undergo a rigorous inspection and measurement process prior to acceptance.


Mass Flow Controllers, utilized for both TEOST™ 33C and MHT™ tests, introduce various components to the test oil such as reactive gases and air.  The MHT™ Mass Flow Controller solely operates with the D7097 test, while the 33C/Dual Mass Flow Controller operates with both ASTM D6335 & D7097 tests.


The TESOT MHT™ test utilizes Depositor Rods with a wire-wound center.