{"id":813,"date":"2026-07-08T07:32:27","date_gmt":"2026-07-08T11:32:27","guid":{"rendered":"https:\/\/www.worldsbestdieseloil.com\/oil-guide\/1985-cadillac-fleetwood-4-3l-6-cyl-diesel-maintenance-guide\/"},"modified":"2026-07-08T07:32:27","modified_gmt":"2026-07-08T11:32:27","slug":"1985-cadillac-fleetwood-4-3l-6-cyl-diesel-maintenance-guide","status":"publish","type":"post","link":"https:\/\/www.worldsbestdieseloil.com\/oil-guide\/1985-cadillac-fleetwood-4-3l-6-cyl-diesel-maintenance-guide\/","title":{"rendered":"1985 Cadillac Fleetwood 4.3L Diesel Maintenance Guide: Oil & Filter Specs"},"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 1985 Cadillac Fleetwood 4.3L Diesel take?<\/h2>\n

The 1985 Cadillac Fleetwood with the 4.3L 6-cylinder (Engine Code T) diesel engine requires an oil viscosity of 10W-30 for temperatures below 16\u00b0C, 15W-40 for temperatures between -18 to 16\u00b0C, or 30 for continuous driving above 0\u00b0C. The oil capacity is 6 quarts with a filter change. AMSOIL recommends using their Signature Series or Heavy-Duty synthetic diesel oils for optimal protection.<\/p>\n

AMSOIL product recommendations<\/h2>\n

Based on the vehicle specifications, the following AMSOIL products are recommended for your Cadillac Fleetwood diesel engine and cooling system:<\/p>\n

Engine Oil Recommendations<\/h3>\n
\n\n\n\n\n\n
Product Name<\/th>\nPart Code<\/th>\n<\/tr>\n
AMSOIL Signature Series 10W-30 100% Synthetic Max-Duty Diesel Oil<\/td>\nDTTQT-EA<\/a><\/td>\n<\/tr>\n
AMSOIL 10W-30 Heavy-Duty 100% Synthetic Diesel Oil<\/td>\nADNQT-EA<\/a><\/td>\n<\/tr>\n
AMSOIL Signature Series 5W-30 100% Synthetic Max-Duty Diesel Oil<\/td>\nDHDQT-EA<\/a><\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Oil Filter Recommendations<\/h3>\n
\n\n\n\n\n\n
Product Name<\/th>\nPart Code<\/th>\n<\/tr>\n
AMSOIL Oil Filter<\/td>\nEAO23-EA<\/a><\/td>\n<\/tr>\n
WIX XP Oil Filter<\/td>\n51036XP-EA<\/a><\/td>\n<\/tr>\n
WIX Oil Filter<\/td>\n51036-EA<\/a><\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Coolant & Transmission Fluid<\/h3>\n
\n\n\n\n\n\n\n
Product Name<\/th>\nPart Code<\/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
AMSOIL Signature Series Fuel-Efficient 100% Synthetic ATF<\/td>\nATLPK-EA<\/a><\/td>\n<\/tr>\n
AMSOIL OE Fuel-Efficient 100% Synthetic ATF<\/td>\nOTLQT-EA<\/a><\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Engine Oil Specifications & Details<\/h2>\n

Proper lubrication is critical for the longevity of the 4.3L diesel engine. Always verify your specific operating temperature before selecting a viscosity.<\/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 (Continuous Driving)<\/td>\n30<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

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

Service Capacities & Torque<\/h3>\n
\n\n\n\n\n
Component<\/th>\nCapacity \/ Spec<\/th>\n<\/tr>\n
Engine Oil Capacity<\/td>\n6 quarts (with filter)<\/td>\n<\/tr>\n
Oil Drain Plug Torque<\/td>\n30 ft\/lbs<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Note: After refilling, always check the oil level manually.<\/em><\/p>\n

Automatic Transmission Fluid (ATF) Details<\/h2>\n

The 1985 Cadillac Fleetwood uses a THM440 transmission. Note that manufacturer technical service bulletins may have updated specifications.<\/p>\n

\n\n\n\n\n\n\n
Specification\/Note<\/th>\nDetails<\/th>\n<\/tr>\n
Transmission Type<\/td>\nTHM440<\/td>\n<\/tr>\n
Updated Spec Note<\/td>\nDexron II or III updated to Dexron VI per manufacturer TSB<\/td>\n<\/tr>\n
Total Fill Capacity<\/td>\n11.1 quarts<\/td>\n<\/tr>\n
Initial Fill Capacity<\/td>\n6 quarts<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Coolant Specifications<\/h2>\n

Maintaining the cooling system is vital for diesel engine efficiency and preventing overheating.<\/p>\n

\n\n\n\n
Component<\/th>\nCapacity \/ Note<\/th>\n<\/tr>\n
Coolant Capacity<\/td>\n13.7 quarts<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

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