{"id":902,"date":"2026-07-11T09:17:24","date_gmt":"2026-07-11T13:17:24","guid":{"rendered":"https:\/\/www.worldsbestdieseloil.com\/oil-guide\/1981-cadillac-seville-5-7l-8-cyl-diesel-maintenance-guide\/"},"modified":"2026-07-11T09:17:24","modified_gmt":"2026-07-11T13:17:24","slug":"1981-cadillac-seville-5-7l-8-cyl-diesel-maintenance-guide","status":"publish","type":"post","link":"https:\/\/www.worldsbestdieseloil.com\/oil-guide\/1981-cadillac-seville-5-7l-8-cyl-diesel-maintenance-guide\/","title":{"rendered":"1981 Cadillac Seville 5.7L Diesel Maintenance Guide: Oil & Fluid Specs"},"content":{"rendered":"
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AMSOIL diesel oil guide for trucks, vans, SUVs and diesel engines<\/figcaption><\/figure>\n

For the 1981 Cadillac Seville with the 5.7L 8-cylinder Diesel engine (Engine Code N), the oil capacity is 7 quarts<\/strong> (including filter replacement). Recommended viscosities include 10W-30<\/strong> for temperatures below 16\u00b0C, 15W-40<\/strong> for -18\u00b0C to 16\u00b0C, and 30 weight<\/strong> for continuous driving above 0\u00b0C. AMSOIL recommends using Signature Series 10W-30 Max-Duty Diesel Oil<\/a> and the EAO64-EA Oil Filter<\/a>.<\/p>\n

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

The 1981 Cadillac Seville 5.7L diesel (Engine Code N) requires an oil with a CF specification. Depending on your operating temperature, you should select the appropriate viscosity: 10W-30 for temperatures below 16\u00b0C, 15W-40 for -18\u00b0C to 16\u00b0C, or a 30 weight oil for continuous driving above 0\u00b0C.<\/p>\n

AMSOIL product recommendations<\/h2>\n

Based on the vehicle specifications, AMSOIL offers several high-performance lubrication options to maintain this GM diesel engine and its associated components.<\/p>\n

Engine Oil Options<\/h3>\n
\n\n\n\n\n\n
Product Name<\/th>\nViscosity<\/th>\nCode<\/th>\n<\/tr>\n
AMSOIL Signature Series Max-Duty Diesel Oil<\/td>\n10W-30<\/a><\/td>\nDTTQT-EA<\/a><\/td>\n<\/tr>\n
AMSOIL 10W-30 Heavy-Duty Diesel Oil<\/td>\n10W-30<\/a><\/td>\nADNQT-EA<\/a><\/td>\n<\/tr>\n
AMSOIL Signature Series Max-Duty Diesel Oil<\/td>\n5W-30<\/a><\/td>\nDHDQT-EA<\/a><\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Oil Filter Recommendation<\/h3>\n
\n\n\n\n
Product Name<\/th>\nCode<\/th>\n<\/tr>\n
AMSOIL Oil Filter<\/td>\nEAO64-EA<\/a><\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Coolant & Antifreeze<\/h3>\n
\n\n\n\n\n
Product Name<\/th>\nCode<\/th>\n<\/tr>\n
AMSOIL Passenger Car & Light Truck Antifreeze & Coolant<\/td>\nANTPC1G-EA<\/a><\/td>\n<\/tr>\n
AMSOIL Propylene Glycol Antifreeze and Engine Coolant<\/td>\nANT1G-EA<\/a><\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Transmission & Gear Fluids<\/h3>\n
\n\n\n\n\n\n\n
Component<\/th>\nProduct Name<\/th>\nCode<\/th>\n<\/tr>\n
Automatic Transmission<\/td>\nAMSOIL Signature Series Fuel-Efficient ATF<\/td>\nATLPK-EA<\/a><\/td>\n<\/tr>\n
Automatic Transmission<\/td>\nAMSOIL OE Fuel-Efficient ATF<\/td>\nOTLQT-EA<\/a><\/td>\n<\/tr>\n
Front Differential<\/td>\nAMSOIL SEVERE GEAR 80W-90<\/a><\/td>\nAGLPK-EA<\/a><\/td>\n<\/tr>\n
Front Differential<\/td>\nAMSOIL SEVERE GEAR 75W-90<\/a><\/td>\nSVGPK-EA<\/a><\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Engine Oil Specifications<\/h3>\n
\n\n\n\n\n
Specification<\/th>\nDetails<\/th>\n<\/tr>\n
Oil Grade<\/td>\nCF<\/td>\n<\/tr>\n
Drain Plug Torque<\/td>\n30 ft\/lbs<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Engine Oil Capacity<\/h3>\n
\n\n\n\n
Condition<\/th>\nCapacity<\/th>\n<\/tr>\n
With Filter Change<\/td>\n7 quarts<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

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

How much oil and coolant does it take?<\/h2>\n

The engine requires 7 quarts of oil when performing a service with a filter change. For the cooling system, capacity varies by regional specification: California models typically require 18.5 quarts, while Federal models require 22.2 quarts.<\/p>\n

Coolant Capacity<\/h3>\n
\n\n\n\n\n
Region<\/th>\nCapacity<\/th>\n<\/tr>\n
California<\/td>\n18.5 quarts<\/td>\n<\/tr>\n
Federal<\/td>\n22.2 quarts<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Automatic Transmission Fluid Specifications<\/h2>\n

For the automatic transmission (THM325\/AF6), the manufacturer’s technical service bulletin has updated the specification from Dexron II or III to Dexron VI. The total fill capacity for a 3-speed THM325 is 10 quarts, while the initial fill is 5 quarts (the final drive is serviced separately).<\/p>\n

Transmission Capacity<\/h3>\n
\n\n\n\n\n
Service Type<\/th>\nCapacity<\/th>\n<\/tr>\n
3-Speed THM325 Total Fill<\/td>\n10 quarts<\/td>\n<\/tr>\n
Initial Fill<\/td>\n5 quarts<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Differential Lubricant: Front<\/h2>\n

The front differential requires a GL-5 All TEMPS 80W-90 lubricant. The capacity for the front differential is 3.2 pints.<\/p>\n

Front Differential Specs<\/h3>\n
\n\n\n\n
Specification<\/th>\nCapacity<\/th>\n<\/tr>\n
GL-5 All TEMPS<\/td>\n3.2 pints<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Diesel maintenance notes for this vehicle<\/h2>\n

Maintenance of the 1981 Cadillac Seville’s diesel engine requires specialized attention compared to standard gasoline V8 engines. Owners should prioritize fuel filtration, glow plug operation, and compression management. Because this is a 1980s GM diesel powerplant, it is critical to verify exact service intervals for the diesel-specific cooling system and fuel injection components via an owner’s manual or dedicated service guide.<\/p>\n

Common diesel oil-related concerns and how AMSOIL products may help<\/h2>\n
\n\n\n\n\n\n
Concern<\/th>\nWhy it matters<\/th>\nAMSOIL Product<\/th>\nHow it may help<\/th>\nLimitation<\/th>\n<\/tr>\n
Engine Wear<\/td>\nDiesel engines face high pressure and friction.<\/td>\nSignature Series 10W-30<\/a><\/td>\nDelivers up to 6X more wear protection.<\/td>\nRequires proper service intervals.<\/td>\n<\/tr>\n
Contaminants<\/td>\nSmall particles can cause significant damage.<\/td>\nEAO64-EA Filter<\/a><\/td>\n99% efficiency at 20 microns.<\/td>\nFilter must be replaced regularly.<\/td>\n<\/tr>\n
Extreme Temperatures<\/td>\nViscosity changes can affect lubrication.<\/td>\nSignature Series 5W-30<\/a><\/td>\nExcels in extreme temperatures.<\/td>\nNot a substitute for mechanical repair.<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Common maintenance concerns for this vehicle<\/h2>\n

Based on historical data, owners of this era of Cadillac should consider the following:<\/p>\n