{"id":667,"date":"2026-06-28T13:11:26","date_gmt":"2026-06-28T17:11:26","guid":{"rendered":"https:\/\/www.worldsbestdieseloil.com\/oil-guide\/1981-buick-century-5-7l-8-cyl-diesel-maintenance-guide\/"},"modified":"2026-06-28T13:11:26","modified_gmt":"2026-06-28T17:11:26","slug":"1981-buick-century-5-7l-8-cyl-diesel-maintenance-guide","status":"publish","type":"post","link":"https:\/\/www.worldsbestdieseloil.com\/oil-guide\/1981-buick-century-5-7l-8-cyl-diesel-maintenance-guide\/","title":{"rendered":"1981 Buick Century 5.7L Diesel Maintenance Guide: Oil, Filters & Fluids"},"content":{"rendered":"
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\"AMSOIL
AMSOIL diesel oil guide for trucks, vans, SUVs and diesel engines<\/figcaption><\/figure>\n

What oil does a 1981 Buick Century 5.7L Diesel take?<\/h2>\n

For the 1981 Buick Century with the 5.7L 8-cylinder diesel engine (Code N), the required oil capacity is 5.9 quarts<\/strong> including the filter. Recommended viscosities include 10W-30<\/strong> for temperatures below 16\u00b0C, 15W-40<\/strong> for -18 to 16\u00b0C, and 30 weight<\/strong> for continuous driving above 0\u00b0C. AMSOIL recommends using high-quality synthetic diesel oils like Signature Series 10W-30<\/a> or Signature Series 5W-30<\/a> for superior protection.<\/p>\n

AMSOIL product recommendations<\/h2>\n

To simplify your maintenance, AMSOIL offers complete oil change kits and individual high-performance fluids specifically selected for this diesel engine application.<\/p>\n

Engine Oil & Filter Kits<\/h3>\n
\n\n\n\n\n\n
Kit Description<\/th>\nIncludes<\/th>\nProduct Code<\/th>\n<\/tr>\n
Signature Series Max-Duty Kit<\/td>\n5W-30 Synthetic Diesel Oil &amp; Filter<\/a><\/td>\nKit Selection<\/a><\/td>\n<\/tr>\n
Signature Series Max-Duty Kit<\/td>\n10W-30 Synthetic Diesel Oil &amp; Filter<\/a><\/td>\nKit Selection<\/a><\/td>\n<\/tr>\n
Heavy-Duty Synthetic Kit<\/td>\n10W-30 Diesel Oil &amp; Filter<\/a><\/td>\nKit Selection<\/a><\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Individual Component Recommendations<\/h3>\n
\n\n\n\n\n\n\n\n\n
Component<\/th>\nAMSOIL Product<\/th>\nPart Number<\/th>\n<\/tr>\n
Engine Oil<\/td>\nSignature Series 10W-30 Max-Duty<\/a><\/td>\nDTTQT-EA<\/a><\/td>\n<\/tr>\n
Engine Oil<\/td>\nSignature Series 5W-30 Max-Duty<\/a><\/td>\nDHDQT-EA<\/a><\/td>\n<\/tr>\n
Engine Oil<\/td>\nHeavy-Duty 10W-30 Synthetic<\/a><\/td>\nADNQT-EA<\/a><\/td>\n<\/tr>\n
Oil Filter<\/td>\nAMSOIL Oil Filter<\/td>\nEAO64-EA<\/a><\/td>\n<\/tr>\n
Coolant<\/td>\nPassenger Car & Light Truck<\/td>\nANTPC1G-EA<\/a><\/td>\n<\/tr>\n
Coolant<\/td>\nPropylene Glycol Antifreeze<\/td>\nANT1G-EA<\/a><\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Engine Oil Specifications<\/h2>\n

Maintaining the correct oil viscosity is critical for diesel engine longevity, especially when managing temperature fluctuations and heavy workloads.<\/p>\n

Oil Viscosity Guide<\/h3>\n
\n\n\n\n\n\n
Temperature Range<\/th>\nRecommended Viscosity<\/th>\n<\/tr>\n
Below 16\u00b0C<\/td>\n10W-30<\/td>\n<\/tr>\n
-18 to 16\u00b0C<\/td>\n15W-40<\/td>\n<\/tr>\n
Above 0\u00b0C<\/td>\n30 (Preferred for continuous driving)<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Oil Grade:<\/strong> CF<\/p>\n

Engine Oil Capacity & Torque<\/h3>\n
\n\n\n\n\n
Measurement<\/th>\nValue<\/th>\n<\/tr>\n
Capacity (with filter)<\/td>\n5.9 quarts<\/td>\n<\/tr>\n
Oil Drain Plug Torque<\/td>\n30 ft\/lbs<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Note: Always check the oil level after refilling.<\/em><\/p>\n

Automatic Transmission Fluid Specifications<\/h2>\n

The 1981 Buick Century uses various 3-speed automatic transmissions. Note that manufacturer technical service bulletins have updated specifications for these units.<\/p>\n

Transmission Capacity & Specs<\/h3>\n
\n\n\n\n\n\n\n
Transmission Model<\/th>\nTotal Fill<\/th>\nInitial Fill<\/th>\n<\/tr>\n
THM250C<\/td>\n10.8 quarts<\/td>\n4 quarts<\/td>\n<\/tr>\n
THM200C<\/td>\n9.4 quarts<\/td>\n3.5 quarts<\/td>\n<\/tr>\n
THM350C<\/td>\n10 quarts<\/td>\n3 quarts<\/td>\n<\/tr>\n
THM350<\/td>\n10 quarts<\/td>\n3 quarts<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Important Note:<\/strong> The AMSOIL lookup note indicates that for these transmissions, the specification has been updated from Dexron II or III to Dexron VI<\/strong> per a manufacturer Technical Service Bulletin.<\/p>\n

Recommended ATF Products<\/h3>\n
\n\n\n\n\n
Product Name<\/th>\nPart Number<\/th>\n<\/tr>\n
Signature Series Fuel-Efficient Synthetic ATF<\/td>\nATLPK-EA<\/a><\/td>\n<\/tr>\n
OE Fuel-Efficient Synthetic ATF<\/td>\nOTLQT-EA<\/a><\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Coolant Specifications<\/h2>\n

Proper cooling system maintenance prevents overheating and protects internal engine components from corrosion.<\/p>\n

\n\n\n\n
Measurement<\/th>\nValue<\/th>\n<\/tr>\n
System Capacity<\/td>\n17.4 quarts<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

AMSOIL Coolant Options:<\/strong><\/p>\n