Warranties are nontransferable. The warranty will begin on the date that the product is delivered to the installer or retail customer.

Diesel Doctor Warranty: Transmissions

Diesel Doctor (DD) built transmissions are warranted to be free from defects in material and workmanship to the original purchaser/end user for a period of 24 months with unlimited mileage. This warranty shall terminate at the 2 year anniversary date from the time of the original invoice.DD reserves the right to amend this warranty at any time.

DD’S liability under this warranty is limited to repair or replacement, at its option, subject to the provisions set forth herein of any parts, which upon examination by DD, are found to be defective. DD reserves the right to determine the course of action in regard to repair and/or replacement of any and all warrantable transmissions.

During the first 90 days of warranty, DD will arrange shipping and will reimburse R&R labor charges not to exceed $450. This reimbursement will be made only to an authorized automotive repair facility. After the first 90 days and up to 180 days, DD will arrange shipping 1-way only and will not reimburse any R&R labor charges. The customer will be responsible for all R&R charges and shipping costs 1-way. After 180 days, the customer is responsible for all shipping and R&R costs for any warranty work needed. DD will cover all warranted transmission parts and labor. The warranty does not cover any fluids or filters.

What is NOT covered under this warranty?

This warranty shall not apply to any transmission that has been tampered with, improperly installed, damaged as a result of abuse, accident or neglect, improperly repaired or altered by the customer or his agent/tech, or abused resulting in broken, sheared, or fractured shafts and/or gears not as a result of manufacture defects. This warranty shall not apply to any products damaged due to low fluid conditions. DD will not warranty broken, sheared, or fractured shafts and/or drums; or any damage associated with broken shafts or drums unless it is determined by DD that the part failure was a result of a manufacture defect. Should DD determine that damage to customers transmission be a result of customer abuse/maintenance neglect, the customer will be responsible for payment of all parts, labor, R&R and shipping costs prior to receiving their transmission back.

DD will not be liable for towing charges, rental car, travel/lodging expenses or any other claims for special, indirect, or consequential damages that may arise under the provisions of this warranty.


Napa Warranty

Covers parts and Labor on Qualifying Repairs and Services for 24 months/24,000 miles with unlimited mileage.

NAPA Truck Service Centers offer the best over the road warranty in the industry and is honored at over 900 facilities nationwide. The NAPA Truck Service Over the Road Warranty provides coverage on qualifying repairs for 6-months with unlimited mileage for over the road, commercial highway use vehicles. Ask your local NAPA Truck Service Center for a copy of the complete warranty. You can double your warranty to 12-months when you use your NAPA AutoCare EasyPay Credit Card.

For warranty service outside a 100 mile radius from your original repairing location, contact the NAPA AutoCare Warranty Administrator at 888-925-5428. For warranty service inside a 100 mile radius from your original repairing location, please contact your original location for service

Warranty On All Parts and Services Performed
Warranties are nontransferable. The warranty will begin on the date that the product is delivered to the installer or retail customer.

Injector Warranties
All injectors come with a 2 year/unlimited milage warranty

FICM / IDM come with a 1-year warranty from

Engine Warranties
View information.

Manufactures Warranties
Please refer to the manufacturers warranty, typically on the box or with the included packaging. Please email office@diesel911.com for any inquires.

EasyPay-extend warranty to 90 days

NAPA Financing

  • 6-months no interest if paid in full on purchases of $199 or more!
  • 6-month and 12-month financing at participating locations.
  • Extend your Over the Road Warranty to 90 days with unlimited mileage
  • Low Minimum Monthly Payments
  • Simple Credit Application Process
  • Instant Credit Available*
  • New Purchasing Power
  • Exclusive Cardholder Financing Promotions*
  • Doesn’t Tie Up Other Credit Lines
  • Receive your credit card in 7-10 days
  • Statement received within 30 days

Online account management at GE Money

Our shop also offers a 12-month/12,000-mile warranty.

Download our warranty

5 Year / 100,000 miles **

This warranty will cover re-manufactured Short and Long Block Engines that are built by Diesel Doctor, unless otherwise stated. From this page on engines will be referred to as “unit(s)” unless otherwise stated. Fuel Pump, Injectors, and Turbo warranties and warranties on accessories are based on the supplying manufacturer’s warranty. **

** All of the engines rebuilt by Diesel Doctor are machined to higher than factory specifications and hold a 5year non-commercial warranty. Gasket and Fluid leaks are protected under the warranty for 1 year from the purchase date ( parts and labor). Parts are protected for 2 years.. This warranty is limited to 3 years/62,000 miles for parts and labor, and the 2 remaining years or 38,000 miles are for parts only. Labor rates are restricted to $50.00/hr shop rate using Mitchell flat rate times.

Diesel Doctor Commercial Warranty

1 Year / 20,000 miles

(Extended Warranty) This will include vehicles such as: Farm equipment, Taxis, Tow-Trucks, Ambulance or Police vehicles, snow plows, off-highway usage and delivery vehicles.

Accessory warranties, including Turbos and Injectors, are based on the warranty of the supplying manufacturers.

Warrantied labor on parts not re-manufactured by Diesel Doctor (ie. Fuel Pumps, Injectors, or Turbos) is only for a term of 6 months from the purchase date. The Diesel Doctor commercial warranty is limited to 1,000 hours for basic coverage without purchase of extended warranty.

Diesel Doctor Extended Commercial Warranty

3 Year / 60,000 miles

Diesel Doctor’s exclusive extended commercial warranty carries the same premium coverage as the standard warranty. Parts and Labor on seal and gasket leaks are limited to 6 months, labor is limited to 1 year. The Diesel Doctor extended commercial warranty is limited to 2,500 hrs.

Warranty Coverage Details

Diesel Doctor will warrant the original buyer on any unit purchased from defects in materials and workmanship. The rights in course of action, regarding repairs or replacements of any warrantied units, is solely reserved by Diesel Doctor. By entering into this contract with Diesel Doctor, the buyer accepts that there will not be any refunds for units used or installed in any way. Diesel Doctor has full discretion on any compensation or refund regarding unused units. All decisions made by Diesel Doctor are final. If a warranty claim is made, all warrantied units must be returned with complete service history including: proof of purchase with date and invoice, mileage of vehicle at installation, and current mileage of vehicle.

This warranty will be null and void and Diesel Doctor will assume no responsibility of liability on any unit in which a required core has not been returned to Diesel Doctor under this warranty. This warranty will be null and void and Diesel Doctor will assume no responsibility of liability on any unit that holds an invoice with an open balance (i.e. before warrantied repair or replacement is considered by Diesel Doctor, all cores must be returned to Diesel Doctor and all bills must be paid in full).

In the case of a failed unit, the buyer must immediately contact Diesel Doctor to notify them of said failure. The buyer must fill out a Warranty Approval Form after contact has been vested. This form will be faxed or emailed by Diesel Doctor. Further instructions shall be given to buyer once the form has been completed and received by Diesel Doctor. In certain situations, a defective unit must be returned to Diesel Doctor for inspection before a replacement unit will be sent out to buyer.

Once a unit has been inspected by Diesel Doctor and the cause of failure is detected, Diesel Doctor will then give written documentation describing the condition of the unit and decide, to the best of their ability, what caused the failure or malfunction. Diesel Doctor will make the decision on the validity of the warranty claim contingent on the inspection report. The buyer will then be contacted by Diesel Doctor and notified of findings of inspection and subsequent actions that will be taken.

In the case that a unit needs immediate servicing and the buyer opts to not wait for said unit to be returned to Diesel Doctor for further inspection, service, and possible repairs or replacement, it is possible for a replacement unit to be purchased for the full, current MSRP of unit, along with core charge and shipping. If/ when a defunct unit is received by Diesel Doctor, the unit will be reviewed, and the core charge will be refunded to buyer. During review of the unit, it will be inspected for warrantied damage. If the failure is covered under the terms of the warranty, Diesel Doctor will refund the buyer for the full purchased price of the replacement unit. If the failure was caused by any issue not covered under the warranty, charges will be figured based on the parts necessary to return unit to Diesel Doctor standards, and the buyer will receive a refund of the difference (if any) between purchased price of the replacement unit and the cost of parts necessary for repair.

Specific Oil (as required), as par the accompanying documents on unit, MUST be used on unit for warranty to be applicable.


All shop labor rates are set at $50.00 per hour based on Mitchell Labor Guide up to a maximum of $2,000.00 per occurrence. There are no exceptions. Balance of labor is to be paid by customer as a deductible for coverage. There will be no additional costs for shop materials.

Buyer MUST submit attached Warranty Registration Form and return core within 45 days of purchase or warranty will be VOID. We recommend that you also email a copy of the Warranty Registration Form to Diesel Doctor in case any paperwork gets lost in shipping. Buyer also acknowledges that regular scheduled maintenance must be performed on the purchased unit. Diesel Doctor reserves the right to request maintenance records on the purchased unit to validate warranty.

Buyer specifically acknowledges that the unit purchase may require additional accessories/components and must be properly installed or the warranty may be void. The limited warranty will be void and not apply to defects or failures caused by:

1. Accident, abuse, abusive driving or an operation for which it was not designed, or alteration from the original manufacturer’s specifications
2. Incorrect installation
3. Incorrect application and conversions
4. Incorrect Oil is used in unit
5. Unit is run without oil
6. Unit is run out of oil due to seal leaks
7. Neglect or regular maintenance as required to maintain full warranty
8. Only Approved tuners allowed or warranty will be void. Contact us for written list of approved tuners. H&S TUNER IS NOT APPROVED!!!


Buyer also acknowledges that proper maintenance procedures are required to keep the unit in proper working order. Diesel Doctor will not assume any responsibility for the cost of this routine maintenance. The Buyer acknowledges:

1. The buyer must notify Diesel Doctors of any warranty claim prior to repair for assignment of an authorization number
2. All attached documents and tags MUST be read, filled out and followed in order to activate the Warranty
3. Diesel Doctor reserves the right to inspect the unit if a warranty claim has been filed
4. The Buyer may be required to deliver/ship the unit to Diesel Doctor for further inspection where deemed necessary
5. Failure to comply will result in a Voided Warranty
6. Buyer will also be required to fill out a Warranty Approval Form and have it faxed back to Diesel Doctor the same day Diesel Doctor was notified of problem involving the unit
7. Buyer understands that any Warranty Claim may take up to 5 business days before it is resolved
8. Any unit returned for warranty CANNOT be disassembled
9. All warranty inspection work will be performed at Diesel Doctor’s shop 30 Morris St. Whiteville, Tn 38075


This warranty will not cover damages, caused by the following, for re-manufactured engines:

1. Injector or injection pump failure
2. Wrong fluid used in unit
3. Overheating/melted heat tabs (250°F)
4. Improper servicing of engine
5. Engine dusting
6. Melted or cracked pistons from failed injectors or excessive EGT’s  
7. Thrust bearing failures where damage is isolated to rear flange only from converter expansion or incorrect transmission alignment

Proper installation procedures must be followed to avoid accident or injury.

Diesel Doctor’s limited warranty will end after the expiration of time or mileage from the date of the original invoice. Any repairs or replacement will not extend the warranty. The buyer shall be responsible for all defects, thereafter, regardless of cause. Diesel Doctor’s limited warranty is in lieu of all other warranties expressed or implied.


The Buyer agrees that Diesel Doctor will NOT be responsible for:

1. Incidental or consequential damages
2. Lost profits, sales or income
3. Injury to person or property Oil, antifreeze, fluids or other substances
4. Lift, dock or storage fees
5. Telephone calls
6. Freight
7. Substitute transportation, lodging, etc.
8. Unauthorized repairs
9. Towing charges or roadside assistance


**To qualify for the 5 year / 160,000 km (100,000 mi) warranty you must follow all instructions and replace all Parts specified.

All new fluids, gaskets, filters and seals must be used upon installation of all parts. In addition, all applicable coolers, lines and filters must be flushed clean before installation to prevent contamination and premature failure. (This includes but in not limited to radiators, oil coolers, and their associated lines and hoses.) Warranty is void if these procedures are not followed exactly. Engine warranties are void if engine is not installed with all of the following: new water pump, new lubricating oil, and all new filters (oil, air, fuel). Engine warranty is void if not installed with the correct fluids as specified by the manufacturer.


Heavier 15w40 and 5w40 engine oils are recommended for temperatures over 50°F (10°C) and must be used for heavy duty driving and trailer towing. Under normal conditions, the engine oil and filter need to be changed at maximum (6,000 mi) or 6 month intervals (whichever comes first). Under severe conditions, the intervals are sooner at (3,000 mi) or 3 months maximum (whichever comes first). Use the same oil and filter change intervals when using synthetic engine oil. Under no circumstance should synthetic oils be used for the first (9,000 mi) to allow proper seating of the piston rings.
A new oil cooler must be used on every engine should a bearing failure occur, no warranty without receipt of new oil cooler.
This warranty is transferable through private sale and change of ownership as long as certain criteria is met.

1. Previous owner must supply purchaser with all relative service documents, original bill of sale and original copy of warranty form.
2. Owner or purchaser must first contact Diesel Doctor to inform of transfer and request a warranty registration Form signed by both parties at time of sale.
3. Warranty transfers have a fee of $500 that must be paid at the time warranty registration form is submitted.
4. Warranty does not start over only continues from time of original purchase.
5. Warranty is only transferable within first 3 years. This does not include fluid/ seal leaks.


Your Tow/Haul and Tow/Haul HD Series standard warranty is:
5 year / 100,000 miles

Our warranty covers our remanufactured Long Block Tow/Haul and Tow/Haul HD Series engines for a period of 2 years 25,000 miles parts and labor, remaining 3 years 75,000 miles parts only. Gasket and seal leaks are limited to 6 months parts and labor, 1-year parts. Head Gasket warranty is limited to 1 year 12,500 miles parts and labor 2-years 40,000 km parts only.

Your Race Series standard warranty is:
6 months/ 3,000 miles PARTS ONLY

Our warranty covers our remanufactured short and long block Race Series engines for a period of 6 months and 3,000 miles parts only, whichever comes first. No warranty on gasket or seal leaks including head gasket failure. Proper retorque and assembly procedures may be required for some models, please refer to all documentation supplied with engine at time of install.

**Extended commercial warranties are not available on Tow/Haul, Tow/Haul HD or Race Series engines.

These applications are a “severe duty” application as stated in Diesel Doctor’s standard warranty package and requires more frequent service intervals which CANNOT exceed;

  • 300 miles before first oil and oil filter change after installation
  • 3,000 miles or 3 months (whichever comes first) oil change intervals
  • 6,000 miles air filter replacement


Diesel Doctor’s limited warranty for Tow/Haul, Tow/Haul HD and Race Series engines is in addition to all items listed in standard warranty package and supersedes all mileage requirements. The limited warranty specifically DOES NOT cover the following damages:

1. Cracked pistons
2. Melted pistons
3. Holes eroded in pistons
4. Engine overspeed causing rod bolt failure
5. Bent connecting rods
6. Broken crankshafts
7. Cracked cylinder heads
8. Failed thrust bearing isolated to rear flange
9. Cylinder washing from fuel flooding