Major oil refiners are feeling the pinch of the Carter administration's voluntary price standard.

Union Oil Co. of California has cut its gasoline prices 6 cents a gallon and its heating oil and diesel fuel prices 7 cents within the last two weeks to stay in compliance with the guideline.

Yesterday Mobil Oil Corp. announced it is trimming its prices for gasoline and jet fuel by 2 cents a gallon and for heating oil and diesel fuel by 3 cents a gallon.

Mobil said the action was necessary to stay within the profit-margin limits set recently under terms of its agreement with the price standard in the third quarter of last year.

As part of that agreement, Mobil said it would hold its revenues $30 million below what it otherwise could receive in the second and third quarters of this year and still be in compliance with the Council on Wage and Price Stability standard.

The Mobil and Union reductions were more striking in the wake of the $2-a-barrel increase in oil prices charged by most oil exporters in recent days.

Because of the increase set by Saudi Arabia, Exxon Corp. said yesterday it is raising its prices for gasoline by 2 cents a gallon and for heating oil and distillates by 4 cents.

It's hard to say how these changes, up and down, will affect the prices motorists pay at the pump.

Retail service station dealers are allowed to charge 16.1 cents a gallon more the the wholesale price they pay. If a Union or Mobil dealer has been meeting competition by taking a smaller margin, he wouldn't have to pass on all the reduction, and might not pass on any of it until he has sold all the gasoline he bought at the higher wholesale price.