{"id":391,"date":"2026-06-07T20:56:46","date_gmt":"2026-06-08T00:56:46","guid":{"rendered":"https:\/\/www.worldsbestdieseloil.com\/oil-guide\/1985-buick-century-4-3l-6-cyl-diesel-maintenance-guide\/"},"modified":"2026-06-07T20:56:46","modified_gmt":"2026-06-08T00:56:46","slug":"1985-buick-century-4-3l-6-cyl-diesel-maintenance-guide","status":"publish","type":"post","link":"https:\/\/www.worldsbestdieseloil.com\/oil-guide\/1985-buick-century-4-3l-6-cyl-diesel-maintenance-guide\/","title":{"rendered":"1985 Buick Century 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

For the 1985 Buick Century with the 4.3L 6-cylinder Engine Code [T] T Diesel, the oil capacity is 5.9 quarts<\/strong> (including filter replacement). Recommended viscosities include 10W-30<\/strong> for temperatures below 16\u00b0C, 15W-40<\/strong> for -18 to 16\u00b0C, and 30<\/strong> weight for continuous driving above 0\u00b0C. AMSOIL recommends using high-performance synthetic diesel oils like Signature Series 10W-30 Max-Duty Diesel Oil<\/a> for superior protection.<\/p>\n

What oil does a 1985 Buick Century 4.3L Diesel take?<\/h2>\n

The 1985 Buick Century with the 4.3L 6-cylinder diesel engine requires an oil grade of CF. Depending on your operating temperature, you should select between 10W-30 (below 16\u00b0C), 15W-40 (-18 to 16\u00b0C), or a 30 weight oil for continuous driving above 0\u00b0C. Always verify the current oil level after refilling.<\/p>\n

AMSOIL product recommendations<\/h2>\n

Based on the AMSOIL lookup for your 1985 Buick Century 4.3L Diesel, here are the recommended fluids and filters to maintain engine health and performance.<\/p>\n

Engine Oil Recommendations<\/h3>\n
\n\n\n\n\n\n
Product Name<\/th>\nViscosity<\/th>\nProduct Code<\/th>\n<\/tr>\n
AMSOIL Signature Series 10W-30 100% Synthetic Max-Duty Diesel Oil<\/td>\n10W-30<\/a><\/td>\nDTTQT-EA<\/a><\/td>\n<\/tr>\n
AMSOIL 10W-30 Heavy-Duty 100% Synthetic Diesel Oil<\/td>\n10W-30<\/a><\/td>\nADNQT-EA<\/a><\/td>\n<\/tr>\n
AMSOIL Signature Series 5W-30 100% Synthetic Max-Duty Diesel Oil<\/td>\n5W-30<\/a><\/td>\nDHDQT-EA<\/a><\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Note: Oil Grade CF is specified.<\/em><\/p>\n

Oil Filter Recommendations<\/h3>\n
\n\n\n\n\n\n
Product Name<\/th>\nProduct 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 Recommendations<\/h3>\n
\n\n\n\n\n\n\n
Component<\/th>\nProduct Name<\/th>\nProduct Code<\/th>\n<\/tr>\n
Coolant<\/td>\nAMSOIL Passenger Car & Light Truck Antifreeze & Coolant<\/td>\nANTPC1G-EA<\/a><\/td>\n<\/tr>\n
Coolant<\/td>\nAMSOIL Propylene Glycol Antifreeze and Engine Coolant<\/td>\nANT1G-EA<\/a><\/td>\n<\/tr>\n
ATF<\/td>\nAMSOIL Signature Series Fuel-Efficient 100% Synthetic ATF<\/td>\nATLPK-EA<\/a><\/td>\n<\/tr>\n
ATF<\/td>\nAMSOIL OE Fuel-Efficient 100% Synthetic ATF<\/td>\nOTLQT-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>\n26 ft\/lbs<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

Oil Capacity Details<\/h3>\n
\n\n\n\n
Condition<\/th>\nCapacity<\/th>\n<\/tr>\n
With Filter Change<\/td>\n5.9 quarts<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

How much oil does it take with a filter change?<\/h2>\n

A complete oil service for the 4.3L diesel engine requires approximately 5.9 quarts of oil when replacing the filter. It is essential to check the oil level using the dipstick after refilling to ensure accuracy and prevent overfilling or underfilling.<\/p>\n

Automatic Transmission Fluid Specifications<\/h2>\n

For vehicles equipped with the THM125C automatic transmission, the AMSOIL lookup notes that this specification has been updated from Dexron II or III to Dexron VI per a manufacturer Technical Service Bulletin. <\/p>\n

\n\n\n\n\n
Transmission Type<\/th>\nCapacity<\/th>\n<\/tr>\n
3-speed THM125C (Total Fill)<\/td>\n7 quarts<\/td>\n<\/tr>\n
Initial Fill<\/td>\n4 quarts<\/td>\n<\/tr>\n<\/table>\n<\/div>\n

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

Maintaining a vintage diesel engine requires attention to several critical systems. Based on technical research, owners should prioritize the following:<\/p>\n