What oil does a 1985 Buick Regal 5.7L Diesel take?
The 1985 Buick Regal with the 5.7L 8-cylinder Engine Code [N] requires an oil capacity of 7 quarts (including filter change). Recommended viscosities include 10W-30 for temperatures below 16°C, 15W-40 for -18 to 16°C, and 30 weight for continuous driving above 0°C. AMSOIL recommends using high-quality synthetic diesel oils like the Signature Series for maximum protection.
AMSOIL product recommendations
Based on the vehicle specifications, here are the recommended AMSOIL products for your 1985 Buick Regal Diesel.
Engine Oil Recommendations
| Product Name | Viscosity | Product Code |
|---|---|---|
| AMSOIL Signature Series Max-Duty Diesel Oil | 10W-30 | DTTQT-EA |
| AMSOIL Signature Series Max-Duty Diesel Oil | 5W-30 | DHDQT-EA |
| AMSOIL Heavy-Duty 100% Synthetic Diesel Oil | 10W-30 | ADNQT-EA |
Oil Filter Recommendation
| Product Name | Product Code |
|---|---|
| AMSOIL Oil Filter | EAO64-EA |
Coolant & Antifreeze Recommendations
| Product Name | Product Code |
|---|---|
| AMSOIL Passenger Car & Light Truck Antifreeze & Coolant | ANTPC1G-EA |
| AMSOIL Propylene Glycol Antifreeze and Engine Coolant | ANT1G-EA |
Automatic Transmission Fluid (ATF) Recommendations
| Product Name | Product Code |
|---|---|
| AMSOIL Signature Series Fuel-Efficient ATF | ATLPK-EA |
| AMSOIL OE Fuel-Efficient ATF | OTLQT-EA |
Engine Oil Specifications & Details
Proper lubrication is critical for the longevity of the 5.7L diesel engine. Always verify your current oil level after a refill.
Oil Viscosity Guide
| Temperature Range | Recommended Viscosity |
|---|---|
| Below 16°C | 10W-30 |
| -18 to 16°C | 15W-40 |
| Above 0°C (Continuous Driving) | 30 |
Oil Grade: CF
Engine Oil Capacity
| Condition | Capacity |
|---|---|
| With Filter Change | 7 quarts |
Note: After refill, always check the oil level manually.
Automatic Transmission Fluid Specifications
The 1985 Buick Regal uses several different transmission models. The AMSOIL lookup notes that for these applications, the specification has been updated from Dexron II or III to Dexron VI per a manufacturer Technical Service Bulletin.
Transmission Capacity & Models
| Transmission Model | Initial Fill | Total Fill |
|---|---|---|
| THM200-4R (4 Speed) | 5 quarts | 11 quarts |
| THM325-4L (4 Speed) | 3.2 quarts | 10 quarts |
| THM250C (3 Speed) | 4 quarts | 10.8 quarts |
| THM200C (3 Speed) | 3.5 quarts | 9.4 quarts |
Diesel maintenance notes for this vehicle
Given the historical context of GM V8 diesel engines from 1978–1985, owners should prioritize rigorous adherence to fuel system maintenance and cooling system integrity. Monitoring for common failure points associated with this engine architecture is critical for longevity. Because these older diesel designs can be sensitive, verifying the correct grade of diesel-specific lubricants is highly recommended.
Common diesel oil-related concerns and how AMSOIL products may help
Maintaining an older diesel engine requires addressing specific operational challenges through high-quality lubrication.
| Concern | Why it matters | AMSOIL Product | How it may help | Limitation |
|---|---|---|---|---|
| Engine Wear | Diesel engines face high pressure and friction. | DTTQT-EA | Delivers up to 6X more wear protection. | Does not repair existing damage. |
| Contaminants | Small particles can cause abrasive wear. | EAO64-EA | 99% efficiency at 20 microns. | Requires regular replacement intervals. |
| Extreme Temperatures | Viscosity changes can affect lubrication. | DHDQT-EA | Excels in extreme temperatures. | Must match required viscosity grade. |
Common maintenance concerns for this vehicle
Based on NHTSA consumer reports, owners of the 1985 Buick Regal have noted several areas requiring attention:
- Engine and Cooling: Reports include concerns regarding carbon monoxide entering the passenger compartment near heater hose connections.
- Steering: Some complaints mention steering feel or control issues.
- Braking: Instances of brake pedal travel issues have been reported.
- Vehicle Speed Control: Historical recall data (86V030000) addressed throttle return spring assembly failures.
Note: NHTSA complaints are owner reports and should not be treated as verified defects.
Recall, TSB, and manufacturer communication notes
The following official recalls were identified for the 1985 Buick Regal:
- Throttle Return Spring (Campaign 86V030000): The assembly may fail, preventing the throttle from returning to idle.
- Tie Rod Assembly (Campaign 84V124000): Bolts fastening tie rods to adjusters may not be tight enough.
- Certification Labels (Campaign 85V114000): Door labels may lack required federal certification statements.
Important: Always verify open recalls by using your specific VIN through the NHTSA website or a certified Buick dealer.
About this vehicle
The 1985 Buick Regal is a mid-size automobile that represents a specific period in General Motors’ history. During this era, the Regal served as a premium intermediate offering within the Buick lineup. This particular model is equipped with a 5.7L V8 diesel engine.
Historically, this engine family was based on the architecture of the Oldsmobile 350 gasoline engine. It is important for owners to note that while General Motors produced various diesel configurations between 1978 and 1985—including V6 and V8 variants—the V8 versions from this period are historically noted for significant reliability challenges. These issues contributed to a decline in the reputation of American light diesel engines during the mid-1980s.
Because specific mechanical tolerances and cooling requirements can vary, owners should verify technical service manuals to confirm precise specifications. Maintaining rigorous fuel system care and monitoring cooling system integrity are essential for those operating this vintage diesel powertrain.
Common questions about this vehicle’s diesel oil and maintenance
How much oil does my 1985 Buick Regal 5.7L Diesel take?
It takes 7 quarts of oil when performing a service that includes a filter change.
What is the best oil for continuous driving in this Buick?
For continuous driving at temperatures above 0°C, a 30 weight viscosity is preferred. AMSOIL Signature Series options like DTTQT-EA are designed to maintain proper viscosity.
Can I use Dexron III in my automatic transmission?
The AMSOIL lookup note indicates that for the THM transmissions in this vehicle, the specification has been updated from Dexron II or III to Dexron VI per a manufacturer Technical Service Bulletin.
What should I do if my engine is running hot?
While AMSOIL provides high-quality coolants like ANTPC1G-EA to protect cooling system metals and gaskets, overheating may require mechanical diagnosis of the cooling system.
Does AMSOIL offer a filter for my 5.7L diesel?
Yes, AMSOIL recommends the EAO64-EA oil filter, which provides 99% filtering efficiency at 20 microns.
How do I check for active recalls on my Regal?
You should contact a local dealer or visit the NHTSA website and provide your Vehicle Identification Number (VIN) to check for any outstanding manufacturer communications or safety recalls.
Disclaimer: This information is derived from provided source data. Always consult your original vehicle owner’s manual or a certified mechanic before performing any service to ensure compatibility with your specific engine and components.