Original record summaries, dates and identifiers for this model-year. Records 501–600 of 1,722, ordered newest first. Dated records on this page: Feb 28, 2020–Nov 25, 2020.
Read the applicability before drawing a conclusion.
This archive includes service bulletins, warranty notices, software instructions and other communications. Records may repeat or supersede earlier instructions. A model-year association is not proof that a document covers every engine, trim, VIN or reported symptom, or that a repair is free.
NHTSA download snapshot: Sep 28, 2026. These are communication associations for this vehicle, not unique defects. How records are joined and counted.
Nov 25, 2020Service Bulletin/Repair Instructions
18NA263
NHTSA communication ID: 10184480
NHTSA source summary · Original PDF not reviewed by Recallfolio
This warranty administration bulletin provide policy information for variable diagnostic time allowances on select labor operations (U.S. Only).
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary Information communication provides information to the technician on the steps to diagnose and repair vehicles that may have a buffeting vibration and/or drone type noise, exhaust tone change, and/or body pressure booming. Replace or repair any of the issue that was found in the inspection. If the vehicle is equipped with a 4.3 liter or 5.3 liter engine an updated exhaust system is now available.
Source components: ENGINE AND ENGINE COOLING:EXHAUST SYSTEM · EQUIPMENT · EQUIPMENT ADAPTIVE/MOBILITY · STRUCTURE.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary Information communication provides information to the technician about the use of J-35616-64B terminal test probe, replacement terminals, and terminated leads. The J-35616-64B is the latest test probe released for checking tension or probing the .64 series terminals. The test probe terminal has been released in the terminal repair kit (J-38125-620H) located in Lear Tray 7 part number 963716-2. There are 5 terminated leads in a package part number is 13505346, which can be ordered through your normal General Motors Customer Care and Aftersales parts channel.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This SKU is a Power Window Regulator and Motor Assembly. The customer communication requested return of unsold inventory to inspect the software. The software may be too sensitive to the position of a locating magnet in the assembly causing the activation of the pinch point threshold prematurely. The window will stay open when it should have closed.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary Information communication provides information to the technician about changing the tire and wheel size on vehicles. General Motors will only support a tire calibration for tires that have been sized, tested and designed for the vehicle in question and its applications. Technician should not use the information that is provided by the antilock braking system tire size selection.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This technical bulletin provides repair information to correct a customer concern of pulsing, grinding, scraping noise from brakes, uneven front brake pad wear.
Source components: SERVICE BRAKES, AIR:DISC:PADS · SERVICE BRAKES, HYDRAULIC:FOUNDATION COMPONENTS:DISC:PADS.
NHTSA source summary · Original PDF not reviewed by Recallfolio
The intent of this technical bulletin is to identify aftermarket ALDL or DLC interface devices as potential sources for causing multiple customer concerns that do not have other diagnostic methods to identify them.
Source components: ELECTRICAL SYSTEM · EQUIPMENT · POWER TRAIN:AUTOMATIC TRANSMISSION.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This bulletin provides information on Engine Concerns that could result from lack of scheduled maintenance, improper service or aftermarket calibrations.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary information communicates the use of air leak diagnostic test tool CH-52250 in addition to the information found in the service manual.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This bulletin provides information on the TOP TIER Detergent Gasoline Licensed Brands and the TOP TIER Diesel Fuel Licensed Brands that are recommended for use in all GM vehicles and the TOP TIER FUELS website URL.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This warranty administration bulletin provides information on Warranty Administration - Customer Concern Not Duplicated (CCND) Labor Operation Numbers.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary information communicates information that will need to be provided to TAC to aid in diagnosing if a vehicle comes in with misfire and DTC Codes P0300 - P0308 and/or P050D
NHTSA source summary · Original PDF not reviewed by Recallfolio
This service bulletin informs the technician to inspect for a possible electrical concern at the ECM X2 electrical connector to correct a customer concern of Malfunction Indicator Lamp (MIL) Illuminated - DTC P0333 Set.
Source components: ELECTRICAL SYSTEM · EXTERIOR LIGHTING.
NHTSA source summary · Original PDF not reviewed by Recallfolio
Special Coverage Adjustment - In some circumstances, some 2014-2018 model year Cadillac Escalade, Chevrolet Silverado, Chevrolet Suburban, Chevrolet Tahoe, GMC Sierra, and GMC Yukon vehicles may have a condition where customers may experience increased brake pedal effort, hard brake pedal, and/or potentially increased stopping distance. The condition is more prevalent at low speed when softly applying the brakes. The engine mounted mechanical vacuum pump output may decrease over time decreasing the amount of vacuum/power brake assist. Failure to follow recommended oil change intervals could contribute to this condition. The Driver?s Information Center, (DIC) ?Service brake assist? alert will activate 2-5 minutes after the vacuum level drops, and a Diagnostic Trouble Code, (DTC) will also be set. Even where this condition occurs, the hydraulic brake system remains functional but may require additional pedal force. Dealers are to replace the vacuum pump and vacuum pump belt. The repairs will be made at no charge to the customer.
Source components: ENGINE · SERVICE BRAKES, HYDRAULIC:PEDALS AND LINKAGES.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Warranty Administration bulletin provides information for dealers/Service advisors on when and how to submit a Pre-Repair Authorization (PRA) (US dealers only).
NHTSA source summary · Original PDF not reviewed by Recallfolio
This technical bulletin provides a procedure for testing the battery cables for voltage drop, Checking for a bad ground at g218, Inspecting for a short at the starter B+ to shield and testing for a faulty battery.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This bulletin provides information on the Transport Mode On Message Being Displayed in the Driver Information Center (DIC) and/or Battery Light is Flashing and the procedures to turn the Transport Mode message ON and OFF.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Bulletin provides the technician with information on how to perform a oil consumption test and a procedure to replace the pistons if found the cause of the oil consumption.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This informational bulletin advises the technician of possible coolant entering the areas of the engine, either through failed parts or defects in the castings, that may be the cause of the concerns related to the MIL or the engine running rough.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary information communicates A vehicle may have a concern of DTC P050D setting along with a P0300 after a cold start up. White smoke and/or coolant odor may come from exhaust for an extended period of time at cold start as well. Cause Coolant getting into the cylinders, and provides direction for the repair.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Warranty Administration bulletin provides information on Global Warranty Management (GWM) Warranty Parts Center (WPC) Parts Return Program Information.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This bulletin provides information on the Transport Mode On Message Being Displayed in the Driver Information Center (DIC) and/or Battery Light is Flashing and the procedures to turn the Transport Mode message ON and OFF.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This informational bulletin explains possible normal condition of a flare from 1st to 2nd, even if the trans had been repaired for the flare and its still noticed.
Source components: POWER TRAIN:AUTOMATIC TRANSMISSION.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This bulletin provides information for use on a Product Assistance Claim (PAC), which is formerly known as a Product Allegation Resolution (PAR) claim.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary Information communication provides information to the technician that General Motors Technical Assistance Center may ask for Global Diagnostic System 2 Session Log. Technician will need use Global Diagnostic System 2 to send the session logs to General Motors Technical Assistance Center for further assistance on the vehicle in question.
NHTSA source summary · Original PDF not reviewed by Recallfolio
Special Coverage Adjustment - certain vehicles with a 6.2L engine may have a condition that affects the electrical connection to the transmission oil temperature sensor. If this condition occurs, rough transmission shifts or hesitation during acceleration may occur. Additionally, the Malfunction Indicator Light (Check Engine Light) would illuminate and a diagnostic trouble code related to the temperature sensor would set. Dealers are to replace the transmission wiring harness as necessary. The repairs will be made at no charge to the customer.
Source components: ELECTRICAL SYSTEM · ENGINE · POWER TRAIN.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Bulletin provides guidelines for Dealers Not Required and for Dealers Required to Contact the PQC for engine or transmission assembly replacement and explains the PQC process, GWM Transaction submission, vehicle service record retention and proper handling of assembly returns for Canadian Dealers only.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary Information communication provides information to the technician about finding needle bearings during an oil change. Technician will gain access to the roller rockers to inspect them. Only replace the roller rocker that is missing needle bearings. Be sure to clean the oil drains to retrieve the needle bearings. Each roller rocker has 66 bearings.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary Information communication provides information to the technician about vehicles that the Heater-Vent-Air Conditioning blows warm air. Before calling General Motors Technical Assistance Center technician will need to have high and low pressures, outside temperature, humidity, and vent temperature.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary Information communication provides information to the technician about vehicles that have an intermittent no crank, no start, or start stall concern with the security light coming on. Technician may find Diagnostic Trouble Codes B3055, B3060, and/or B3935. Technician should not replace any parts for this concern. If unable to duplicate the concern ask if the customer uses any Radio Frequency Identification Devices when the concern is present. Dealer should also direct their customers to the appropriate section in the Owner manuals that references that the device complies.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary Information communication provides information to the technician about vehicles that have a creak, click, pop, and or crack type noise from the front suspension or front frame area while making tight turns. Technician will need to loosen and then re-torque the four front frame cross member nuts and bolts.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This preliminary informational bulletin provides frame coating repair information to correct a customer concern of wax coating on frame peeling, metal shows corrosion/rusting (U.S. and Canada Only).
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary Information communication provides information to the technician that General Motors and General Motors of Canada Company do not support cross border sales. The General Motors of Canada Customer Care Centre is the sole authorized provider of a certification confirmation letter which helps our customers identify if their vehicles meets the required USA regulatory standards necessary for importation into the USA.
NHTSA source summary · Original PDF not reviewed by Recallfolio
Special Coverage (Parts Ordering Information Added). On some vehicles, may have a condition where thermal cycling on the combination transmission fluid/oil and AC condenser cooler creates a crack that may allow refrigerant to escape. This condition consequently may deactivate the AC system which may cause potential customer annoyance. This special coverage covers the condition described above for a period of 5 years or 60,000 miles (100,000 km) for Chevrolet Suburban, Tahoe, GMC Yukon and Yukon XL and 6 years or 72,000 miles (116,000 km) for Cadillac Escalade and Escalade ESV, whichever occurs first, from the date the vehicle was originally placed in service, regardless of ownership. Dealers are to inspect the air conditioning condenser and replace if necessary. The repairs will be made at no charge to the customer.
Source components: ENGINE · ENGINE AND ENGINE COOLING · POWER TRAIN.
NHTSA source summary · Original PDF not reviewed by Recallfolio
Special Coverage (Diagnosis Time Added). On some vehicles, may have a condition where thermal cycling on the combination transmission fluid/oil and AC condenser cooler creates a crack that may allow refrigerant to escape. This condition consequently may deactivate the AC system which may cause potential customer annoyance. This special coverage covers the condition described above for a period of 5 years or 60,000 miles (100,000 km) for Chevrolet Suburban, Tahoe, GMC Yukon and Yukon XL and 6 years or 72,000 miles (116,000 km) for Cadillac Escalade and Escalade ESV, whichever occurs first, from the date the vehicle was originally placed in service, regardless of ownership. Dealers are to inspect the air conditioning condenser and replace if necessary. The repairs will be made at no charge to the customer.
Source components: ENGINE · ENGINE AND ENGINE COOLING · POWER TRAIN.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary information communicates the use of air leak diagnostic test tool CH-52250 in addition to the information found in the service manual.
Source components: ENGINE · ENGINE AND ENGINE COOLING:COOLING SYSTEM · EQUIPMENT.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Bulletin provides the technician with information on how to perform a oil consumption test and a procedure to replace the pistons if found the cause of the oil consumption.
Source components: ENGINE AND ENGINE COOLING:ENGINE:OIL/LUBRICATION · EQUIPMENT.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary Information communication provides information to the technician that General Motors Technical Assistance Center may ask for Global Diagnostic System 2 Session Log. Technician will need use Global Diagnostic System 2 to send the session logs to General Motors Technical Assistance Center for further assistance on the vehicle in question.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This bulletin provides information on Policies Applicable to All U.S. Dealers for Engine and Transmission Assembly Replacement Under Warranty, Policy or Customer Enthusiasm and information on Submission of Warranty Transaction in Global Warranty Management.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary information communicates to the dealer technician that if after replacing the valve body on an 8L45 or 8L90 transmission the vehicle will not move the valve body may be missing a plug and retainer bolt. Technician's are instructed to obtain and install a plug and retainer bolt kit from the GM Warranty Parts Center to address this concern.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary information communicates to the dealer an issue where a customer may have incorrectly received a notification advising of a starting syetem issue with their veihcle. Dealer advised to inspect for a legitimate issue, if one found, diagnose accordingly.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This technical bulletin provides repair information to correct a customer concern of carpet damage, seat mounting stud wear through, hole in second row (Intermediate) carpet.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This warranty administration bulletin provides information on Global Warranty Management (GWM) Warranty Parts Center (WPC) Parts Return Program Information.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This technical bulletin provides repair information to correct a customer concern of forward collision/active safety system inoperative, no messages or alerts. Technician may find DTC?s B390A?45, B390A?58 and/or DTC?B390A?67 are set.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary Information communication provides information to the technician about vehicles that may have a delayed engagement into drive, shudder at a launch, or the transmission is slipping when shifting into 1st, 2nd, 3rd or 4th gears. This may be due to loose stator support to pump cover bolts causing a leak at the stator support to pump cover gasket. Technician will check for the bolts to be loose. If any of the bolts are loose or the gasket is misaligned or leaking, the transmission pump cover must be replaced and the 1234 clutch plates should be inspected for being distressed and repaired as needed.
Source components: ENGINE AND ENGINE COOLING · POWER TRAIN:AUTOMATIC TRANSMISSION:INTERNAL:GEARS.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary Information communication provides information to the technician that General Motors and General Motors of Canada Company do not support cross border sales. The General Motors of Canada Customer Care Centre is the sole authorized provider of a certification confirmation letter which helps our customers identify if their vehicles meets the required USA regulatory standards necessary for importation into the USA.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This technical bulletin provides repair information to correct a customer concern of forward collision/active safety system inoperative, no messages or alerts. Technician may find DTC?s B390A?45, B390A?58 and/or DTC?B390A?67 are set.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This informational bulletin explains the normal noises an engine may make when the ambient temperature outside is cold or the vehicle has sat for a few hours.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This informational bulletin includes information on Interior Cleaning - Instrument Panel (IP), Hard or Plastic Surfaces, Seats, Carpet, Leather, Vinyl, Fabric Cleaner, Stain Remover, Restorer - Product Availability.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary information communicates information that will need to be provided to TAC to aid in diagnosing if a vehicle comes in with misfire and DTC Codes P0300 - P0308 and/or P050D
NHTSA source summary · Original PDF not reviewed by Recallfolio
This technical bulletin advises of a new fuel injection cleaner kit used for decarbonizing the intake valves to correct conditions of rough idle, Crank no start, extended crank or misfire, MIL with DTCs, and explains how Top Tier fuels should be used to reduce carbon build-up.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary information communicates the use of Winter grade fuel during the warm months of 2020 and the potential rivability issues that it can cause. The ongoing Coronavirus (COVID-19) pandemic has caused significant reductions in driving and fuel use. Due to the surplus of winter grade fuel sitting in storage (pipelines/stations) the EPA is waiving the fuel vapor requirement. This will extend the use of winter fuel into the summer months. The drivability concerns should not be single events but should be multiple occurrences associated with hot days.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This informational bulletin includes information on Interior Cleaning - Instrument Panel (IP), Hard or Plastic Surfaces, Seats, Carpet, Leather, Vinyl, Fabric Cleaner, Stain Remover, Restorer - Product Availability.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This informational bulletin explains to the tech on how to order a new fuel injector by matching the part number on the part and ordering it from the EPC.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary information communicates the use of air leak diagnostic test tool CH-52250 in addition to the information found in the service manual.
Source components: ENGINE AND ENGINE COOLING · EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This technical bulletin provides a procedure to repair the valve lifter oil manifold and/or lifters to correct the customers concern of engine misfire, ticking noise and/or MIL Illuminated.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This informational bulletin includes information on Interior Cleaning - Instrument Panel (IP), Hard or Plastic Surfaces, Seats, Carpet, Leather, Vinyl, Fabric Cleaner, Stain Remover, Restorer - Product Availability.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary Information communication provides information to the technician about vehicles that have an intermittent no crank, no start, or start stall concern with the security light coming on. Technician may find Diagnostic Trouble Codes B3055, B3060, and/or B3935. Technician should not replace any parts for this concern. If unable to duplicate the concern ask if the customer uses any Radio Frequency Identification Devices when the concern is present. Dealer should also direct their customers to the appropriate section in the Owner manuals that references that the device complies.
Source components: ENGINE AND ENGINE COOLING · EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This informational bulletin provides information on Normal Radio Display Operation ? Display Does Not Remain Off at Times After Being Turned Off in Settings and no parts should be replaced due to this condition.
Source components: ELECTRICAL SYSTEM · EQUIPMENT:ELECTRICAL:RADIO/TAPE DECK/CD ETC..
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary Information communication advises the technician that the door striker cover will be shipped with the vehicle from the assembly plant. Technician is to make sure the rounded side of the cover is positioned towards the outboard side of the vehicle.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This preliminary informational bulletin provides information to dealership personnel which may be helpful when addressing underbody component corrosion with customers.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary Information communication provides information to the technician about vehicles that have an unwanted Stability Activation and/or a Service Stability message on the Driver Information Center. Technician may find a Diagnostic Trouble Code C0710. Technician should inspect for vehicles modifications before any in-depth diagnostics are performed.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This technical bulletin provides a procedure to validate if the parking pawl actuator is not working as intended, causing the parking pawl to engage while driving.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This warranty administration bulletin explains to the technician that when using wiring repair labor operations, additional information may be needed when submitting Global Warranty transactions when doing wiring repairs.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This technical bulletin provides information for new transmission oil to use and a procedure for exchanging the old fluid and adding the new fluid to correct a shake/shudder during light throttle acceleration condition.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary information communicates instructions dealer to inspect for a broken or damaged side objector sensor/module bracket if there is a "Side Detection System Unavailable" message displayed at startup.
Source components: ELECTRICAL SYSTEM · EQUIPMENT · EQUIPMENT ADAPTIVE/MOBILITY · LANE DEPARTURE: BLIND SPOT DETECTION.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary information communicates an issue where the chassis wiring harness can chaff on the underbody of the vehicle causing a wide varied of issues, depending on which wire(s) is chaffed. Repair the affected wiring as needed
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary Information communication provides information to the technician for a water leak in in the second and third row seating area. Inspect the C-pillar which is the body vertical structure behind the rear passenger door area of the affected side of the vehicle for water intrusion or water marks on the seat belt retractor. If water evidence is found on the seat belt webbing or the retractor the seat belt/ retractor must be replaced after the water leak has been corrected and verified. There are 3 areas of seam sealer that will need to be addressed. After gaining access to the C-pillar and rear quarter panel area inspect for voids or missing seam sealer and apply a clear flow able seam sealer where needed.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This informational bulletin explains the normal noises an engine may make when the ambient temperature outside is cold or the vehicle has sat for a few hours.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This technical bulletin provides a procedure to repair the valve lifter oil manifold and/or lifters to correct the customers concern of engine misfire, ticking noise and/or MIL Illuminated.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary Information communication provides information to the technician about vehicles with tire sidewall irregularities. This is a visual condition that will not affect durability, reliability or performance of the tires. Dealer should communicate to the customer that slight sidewall indentations are a common characteristic of radial tire construction.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This Preliminary Information communication provides information to the technician with the steps to diagnosis and repair vehicles with various handling, vehicle dynamics concerns, noises from the suspension or underbody, or issues related to damaged suspension components. Before any in-depth diagnostics are performed, be aware that various issues could occur if the vehicle has been modified and inform the customer the conditions noted may not be covered under warranty. Technician will inspect for installed aftermarket suspension components. Also inspect for improperly adjusted torsion bars.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This warranty administration bulletin provides information on Warranty Administration ? Customer Concern Not Duplicated (CCND) Labor Operation Numbers.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This warranty administration bulletin provides information on Global Warranty Management (GWM) Warranty Parts Center (WPC) Parts Return Program Information.
NHTSA source summary · Original PDF not reviewed by Recallfolio
This informational bulletin explains Unscheduled Supplemental Services (including Flushing Services and Additives) and the Proper use of GM Simplified Maintenance Schedules.