Oil Specifications for an AMC 304by Kris Ramsay
The American Motor Company (AMC) resulted from the merger of Hudson Motors and Nash-Kelvinator in 1954. In 1970 AMC purchased the Jeep brand. In 1987 AMC was bought out by Chrysler; all that Chrysler kept of the AMC brand was Jeep. During the 33 years that AMC produced cars, one of its stand-out engines was the small-block 304 V-8 that ended up powering many Jeeps.
The 304 small-block V-8 was introduced in 1971 to replace a 290-cubic inch model of the same engine. It was first used to power the Jeep J-Series and Wagoneers; in 1972 it was offered with the Jeep CJ. The engine performed so well, in fact, that CJ frames were modified in 1973 to prevent cracks. The engine was also optional in the AMC Gremlin, Hornet and Javelin.
The 304 had a cylinder bore of 3.75 inches and a stroke of 3.44 inches. The 1971 version was the most powerful with 210 gross horsepower at 4,400 rpm. The 1972-1978 version had 150 ghp at 4,200 rpm; the 1979 version, 130 ghp at 4,200 rpm; and the 1980-1981 version, 125 ghp at 3,200 rpm. All versions had the same compression ratio, which was 8.4:1, and the same oil pressure, which was 50 pounds per square inch (psi) at 2,000 rpm. Fuel delivery was by a two-barrel carburetor.
The crankcase oil capacity for the 304 V-8 was five quarts. The recommended oil weight was 10w30. The torque specifications for the oil pan were 5-8 psi with 1/4-inch bolts and 10-12 psi with 5/16-inch bolts. The torque specification for the drain plug was 25 foot-pounds. The oil-change interval was 3,000 to 5,000 miles or every three to five months.
Different Types of Oil
When the 304 first came out, the only type of oil available was non-synthetic. Scientists have now created synthetic oil, which lasts longer than non-synthetic oil and does a better job of protecting your engine. If you have been using non-synthetic oil in your 304 and wish to upgrade to synthetic, that is perfectly all right.