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Stern Equipment Guard Terms & Conditions

STERN Limited Extended Warranty


Stern Oil Company (“STERN”) proudly stands behind the quality of its product offering. The product line (“Lubricants”) STERN recommends and distributes has been specially formulated with the latest technology to meet and exceed the performance requirements of automotive, agriculture and commercial equipment. 


All Lubricants are warrantied to be free from defects and to protect the critical engine and transmission parts as set forth below (“Critical Parts”) of agricultural or commercial equipment (“Equipment”) from fluid or fuel related failure.  This Limited Warranty is available to consumers, including business entities (“You” or “Your”), that use STERN approved Lubricants and Atomic Diesel in Equipment for at least six (6) consecutive months, one hundred fifty (150) hours or two-thousand five-hundred (2,500) miles, whichever occurs first (“Effective Date”) and continuously thereafter. This Limited Warranty will continue during Your ownership or lease of the Equipment (“Warranty Period”).  The term Equipment specifically excludes vehicles or equipment: (i) modified or used for any type of competitive motorsports activity; (ii) that have had the engine repaired or modified with equipment or parts that would void the manufacturer’s warranty, and (iii) that have been modified with non-factory equipment or accessories (such as a snow plow attachment). 

The critical engine and transmission parts (“Critical Parts”) covered by this warranty are limited to those lubricated or wetted by the Lubricants and fuel.


If a Lubricant or fuel is shown to be defective during the Warranty Period, STERN will replace any defective Lubricant or fuel and, at STERN’s option, pay for either the reasonable cost of repair or replacement of any Critical Part of Your Equipment that was directly damaged by a defect of the Lubricant up to $25,000.  “Damage” shall mean the total mechanical failure of a Critical Part.  STERN may replace or repair Critical Parts with a part that is of like kind and quality, including the use of refurbished or used parts.  In addition to the above requirements, the following terms and conditions must be met to the satisfaction of STERN:

  1. The Lubricant used by You, including the grade and viscosity thereof, was appropriate for the intended use in the Equipment according to the original Equipment manufacturer’s specifications;
  2. You have used STERN approved Lubricants and Atomic Diesel continuously (any interruption in use of STERN approved Lubricants and Atomic Diesel will require You to satisfy the time, hour or miles prerequisite again before the Limited Warranty will apply);
  3. The Equipment is operated under normal operating conditions and in accordance with the operating instructions and limitations, including speed, load and temperature set forth by the manufacturer specified or recommended and approved by STERN for the product in question, whichever standard is more stringent;    
  4. The Equipment is under a program of regular, documented maintenance including, but not limited to, the cooling and lubricating systems in accordance with the manufacturer’s service recommendations;
  5. The failure of the Critical Part , Lubricant, or Fuel was not due to contamination, water or excessively severe conditions;
  6. The Lubricant or fuel used must have been put in service no later than three (3) years from the date of manufacturer;
  7. Lubrication changes have been completed in accordance with the original Equipment manufacturer’s recommended drain and replacement intervals, and additionally in the case of all oils, changed at least one time every twelve (12) months;
  8. The Lubricant or fuel was not used in conjunction with any unauthorized product or additive as determined in the sole discretion of STERN; and
  9. You:
    • Keep all Lubricant and fuel purchase receipts as proof of purchases, and have documentation of the miles/hours at the time the Lubricant was installed, general Equipment repairs, and preventative maintenance activities;
    • Keep all damaged Critical Parts of the Equipment for inspection by STERN and subject matter experts.
    • Allow a STERN representative to inspect the Equipment, including any damaged engine, component or automotive system;
    • Allow random Lubricant and fuel sampling and analysis throughout the Warranty Period; and
    • Cooperate with the STERN investigation of the claim and provide information reasonably requested by STERN.


To file a claim under this Limited Warranty, You must:

  1. Notify STERN at (605)-925-7999 or as soon as You discover any defect in the Lubricant or Damage to a Critical Part, but in any event, no later than sixty (60) days from the date the damage occurred;
  2. Collect a 4-ounce sample of the used Lubricant in question from the Equipment and place into a clean, dry container (STERN sample kits are available at the STERN corporate office at 27923 US HWY 81, Freeman, SD);
  3. Mail, at Your expense, the following items to STERN, Attn: Warranty Claim, 27923 US HWY 81, Freeman, SD 57029;
    • The 4-ounce sample (see above);
    • Documentation describing the make, model and year of the Equipment, and total accumulated miles or hours;
    • The Equipment’s maintenance history documentation, including miles/hours at the time of STERN approved Lubricant installation, general equipment repairs, and oil analysis results;
    • Proof of purchase of STERN approved Lubricant and fuel; and
    • Batch number from the Lubricant container or certificate of analysis (if available).

STERN reserves the right to inspect the damaged Critical Part and Equipment, take Lubricant and fuel samples, perform analyses and examine all related documentation deemed necessary to determine cause of failure.  Failure to allow STERN to do so will result in denial of your warranty claim.


This limited warranty does not cover any damage to critical parts that occurs prior to the effective date or any repair or replacement of critical parts due to normal wear and tear, the failure of any critical part that is related to any pending or completed legal proceeding or recall, or for which the manufacturer has announced its responsibility by any means, or damage to critical parts that are also covered by the equipment’s manufacturer warranty or any extended service contract or warranty.  

Further, this limited warranty does not cover any damage to critical parts that is the result of: collision or other accident; theft; vandalism; riot; explosion; earthquake; lightning; freezing; overheating; internal or external fire; water or flood damage (including prior flood damage); negligent, reckless, knowing or intentional damage; timing belt failure; improper service or maintenance; defect attributable to the vehicle manufacturer; improper installation of any part; fluid contamination (i.e., coolant, fuel, water or foreign material); or the failure to keep the motor oil and engine coolant at levels prescribed by the manufacturer.

The limited warranty provided herein is intended to and will be your only recovery against STERN. STERN excludes and disclaims any and all implied warranties including, but not limited to, implied warranty of fitness for a particular purpose and merchantability. to the maximum extent allowable by law, STERN will not be responsible for special, incidental, punitive or consequential damages including, but not limited to, loss of profits, loss of use, business interruption, cost of towing or lodging, or damages for loss of property or bodily injury. this provision will apply whether the cause of action relates to use of the lubricant or arises out of any services provided under this warranty.  In no event will STERN’s total liability exceed the replacement value of your damaged critical parts. 

STERN may alter, amend, or modify the criteria and terms and conditions of this Limited Warranty at any time and in its sole and absolute discretion.



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