For the 1981 Chevrolet Impala with the 5.7L 8-cylinder Diesel engine (Code N), the oil capacity is 7 quarts (including filter replacement). Recommended viscosities include 10W-30 for temperatures below 16°C, 15W-40 for -18 to 16°C, and SAE 30 is preferred for temperatures above 0°C. AMSOIL recommends using Signature Series Max-Duty Diesel Oil or Heavy-Duty Synthetic Diesel Oil paired with an AMSOIL Oil Filter for optimal protection.
What oil does a 1981 Chevrolet Impala 5.7L Diesel take?
The engine requires an oil with a CF grade specification. Depending on your operating environment, you should select the appropriate viscosity: 10W-30 for temperatures below 16°C, 15W-40 for temperatures between -18 to 16°C, or SAE 30 for temperatures above 0°C (where SAE 30 is preferred).
AMSOIL product recommendations
To ensure your vintage diesel engine receives high-quality lubrication, AMSOIL provides several specialized options. Below are the recommended products for this specific application based on available data.
Engine Oil Recommendations
| Product Name | Viscosity | Part Code |
|---|---|---|
| AMSOIL Signature Series 10W-30 100% Synthetic Max-Duty Diesel Oil | 10W-30 | DTTQT-EA |
| AMSOIL 10W-30 Heavy-Duty 100% Synthetic Diesel Oil | 10W-30 | ADNQT-EA |
| AMSOIL Signature Series 5W-30 100% Synthetic Max-Duty Diesel Oil | 5W-30 | DHDQT-EA |
Oil Filter Recommendation
| Product Name | Part Code |
|---|---|
| AMSOIL Oil Filter | EAO64-EA |
Coolant & Antifreeze Recommendations
| Product Name | Part Code |
|---|---|
| AMSOIL Passenger Car & Light Truck Antifreeze & Coolant | ANTPC1G-EA |
| AMSOIL Propylene Glycol Antifreeze and Engine Coolant | ANT1G-EA |
Automatic Transmission Fluid Recommendations
| Product Name | Part Code |
|---|---|
| AMSOIL Signature Series Fuel-Efficient 100% Synthetic ATF | ATLPK-EA |
| AMSOIL OE Fuel-Efficient 100% Synthetic ATF | OTLQT-EA |
Engine Oil Specifications
| Specification | Details |
|---|---|
| Oil Grade | CF |
Engine Oil Capacity & Torque
| Component | Capacity / Torque |
|---|---|
| Total Oil Capacity (with filter) | 7 quarts |
| Oil Drain Plug Torque | 30 ft/lbs |
Note: Always check the oil level after refilling.
Automatic Transmission Fluid Specifications
The transmission requirements vary by model. For all listed units, the manufacturer’s technical service bulletin has updated the specification from Dexron II or III to Dexron VI.
Transmission Capacities
| Transmission Model | Total Fill Capacity | Initial Fill |
|---|---|---|
| THM200-4R (4 speed) | 11 quarts | 5 quarts |
| THM350C (3 speed) | 10 quarts | 3 quarts |
| THM200C (3 speed) | 9.4 quarts | 3.5 quarts |
| THM250C (3 speed) | 10.8 quarts | 4 quarts |
Coolant Specifications
The cooling system has a total capacity of 16.4 quarts. AMSOIL offers both pre-mixed and concentrated options to maintain temperature regulation and protect engine metals.
Coolant Options
| Product | Type |
|---|---|
| ANTPC1G-EA | Ethylene glycol 50/50 pre-mix formulation |
| ANT1G-EA | Concentrated (requires mixing with distilled or high-quality water) |
Diesel maintenance notes for this vehicle
- Oil Level Verification: Always check the oil level after a refill to ensure accuracy.
- Filter Efficiency: Using an AMSOIL filter like the EAO64-EA provides 99 percent filtering efficiency at 20 microns, which helps reduce engine wear by capturing small contaminants.
- Viscosity Management: Ensure you are using the correct viscosity for your ambient temperature to maintain proper oil thickness and protection.
Common diesel oil-related concerns and how AMSOIL products may help
| Concern | Why it matters | AMSOIL Product | How it may help | Limitation |
|---|---|---|---|---|
| Engine Wear | Diesel engines face high pressure and friction. | Signature Series Diesel Oil | Delivers up to 6X more wear protection. | Requires regular maintenance. |
| Extreme Temperatures | Viscosity changes can affect lubrication. | Heavy-Duty Synthetic Diesel Oil | Excels in extreme temperatures and maintains viscosity. | Not confirmed from source data. |
| Contaminant Buildup | Small particles can cause abrasive wear. | EAO64-EA Filter | Provides 99% efficiency at 20 microns. | Not confirmed from source data. |
Common maintenance concerns for this vehicle
Based on historical context and research, owners of vintage diesel vehicles should prioritize the following:
- Cooling System Integrity: Given the age of these vehicles, monitoring hoses and gaskets is vital.
- Fuel System Cleanliness: Maintaining clean fuel is critical for older diesel injection systems.
- Aging Seals: Monitor for leaks around engine and transmission seals due to rubber degradation over time.
Recall, TSB, and manufacturer communication notes
The following official NHTSA recall information was found for the 1981 Chevrolet Impala:
- Brake System: A recall (Campaign 80V125000) noted that some vehicles may have been assembled with an incorrect brake pedal support bracket designed for diesel engines, which could cause brakes to remain partially applied and overheat.
- Throttle Control: A recall (Campaign 83V077000) identified that the accelerator pump lever retaining pin might loosen, potentially causing the throttle to stick open.
Note: These are official manufacturer recalls. Owners should always verify their specific vehicle’s status by checking the VIN through an authorized dealer or the NHTSA website.
About this vehicle
The 1981 Chevrolet Impala represents a significant era in General Motors’ history, marking a period where the model had transitioned from a high-trim luxury flagship to a primary sedan line following the downsizing trends of the late 1970s. While the Impala is widely recognized as a staple of the Chevrolet lineup, users should exercise caution regarding specific engine configurations.
Regarding the 5.7L 8-cylinder Diesel (Engine Code N), it is important to note that modern terms like “Duramax” are not applicable to this vintage vehicle, as Duramax refers to a much later GM diesel engine family. Because technical documentation for this specific year/model combination can vary, owners should perform thorough verification of their powertrain through VIN decoding or physical inspection before applying specialized modern diesel lubricants.
Maintenance for a vehicle of this age typically focuses on managing aging seals, ensuring cooling system integrity, and maintaining fuel system cleanliness. Owners often research vintage diesel injection requirements to ensure long-term reliability in these classic full-size sedans.
Common questions about this vehicle’s diesel oil and maintenance
How much oil does my 1981 Impala 5.7L Diesel take?
It takes 7 quarts of oil when replacing the filter. Always check the level after refilling.
What is the recommended oil viscosity for this engine?
The AMSOIL lookup recommends 10W-30 for temperatures below 16°C, 15W-40 for -18 to 16°C, and SAE 30 for temperatures above 0°C.
What is the oil drain plug torque specification?
The oil drain plug should be torqued to 30 ft/lbs.
Does my transmission need Dexron VI?
Yes, according to manufacturer technical service bulletins, the specification has been updated from Dexron II or III to Dexron VI for these transmissions.
Can I use a synthetic oil in this vintage diesel?
AMSOIL lists several synthetic options, such as the Signature Series 10W-30 (DTTQT-EA), which is designed to provide superior wear protection and maintain viscosity.
How do I verify if my vehicle has an open recall?
You should always use your specific VIN to check for open recalls through the NHTSA website or a local Chevrolet dealer to ensure safety components like brake brackets or throttle pins are correct.
Disclaimer: Information provided is based on available source data. Always consult your vehicle’s owner manual or a professional mechanic before performing maintenance.