U.S. Ability To Chart Oil Questioned
National Treasury Employees Union, consumer groups and some Congressmen oppose ruling by US Customs Comr Robert E Chasen that customs inspectors who record oil imported by US in tankers accept ullaging reports of public gaugers instead of doing own measuring; say rule change, which is designed to reduce overtime, would eliminate Government's only independent set of oilâimport figures, forcing it to rely of those supplied by oil companies; figures on oil imports from Customs have recently differed sharply from those provided by oil industry; top Customs officials defend ruling while admitting that it may have to be revised; comments by Frank Tague, union president, and Chasen (M)