Ford Motor Co. said yesterday it earned a record $333.1 million in the third quarter, lifting the domestic auto industry's earnings for the period to $1.16 billion.

E. I. du Pont de Nemours also reported strong third-quarter earnings, but Standard Oil Co. (Ohio), the nation's 12th largest oil company, reported its third-quarter profits dropped 11 percent, primarily because of reduced production from Alaska's Prudhoe field and lower crude oil prices.

Ford's third-quarter profit ($1.83 per share) compared with a $325.4 million loss in the same period a year ago.

It was the No. 2 U.S. automaker's best showing for the third quarter. Ford's previous record for that period was $301.4 million in 1978.

Third-quarter sales rose to $10.3 billion from $8.05 billion.

Ford said it earned $1.09 billion ($6) so far this year, compared with a $422 million loss ($2.34) in the first nine months of 1982. Nine-month sales climbed to $32.1 billion from $27.9 billion.

Ford attributed its good showing to improved productivity, better sales of larger, more option-loaded vehicles and stronger car and truck sales worldwide, especially in North America.

Ford also noted that its latest per-share earnings reflected a 3-for-2 stock split announced Oct. 13.

In the third quarter, Cleveland-based Sohio earned $435 million ($1.76), down from $487 million ($1.97) in the same quarter last year. Revenue fell 9 percent to $3 billion from $3.3 billion.

Sohio's income from exploration and production activities slipped 18.7 percent to $780 million from $960 million in the 1982.

Sohio's share of Alaskan oil production dropped to 594,200 barrels a day from 708,500 barrels a day in the third quarter last year. Its stake in the Prudhoe field was reduced after the participating interests held by the three producers--Sohio, Atlantic Richfield Co., and Exxon Corp.--were redetermined.

In the first nine months of 1983 Sohio's earnings were off 16 percent to $1.19 billion ($4.82), from $1.42 billion ($5.74) a year earlier. Revenue dropped 13.5 percent to $8.9 billion from $10.3 billion.

Du Pont said earnings rose 60 percent in the third quarter, its best performance in almost two years, as a result of an expanding economy and cost-cutting programs.

Profit rose to $312 million ($1.30), from $195 million ($1.13) in the third quarter of 1982. The sharp jump in earnings came on a modest rise in sales, to $8.8 billion from $8.2 billion.

For the first nine months of 1983, profit rose 14 percent to $786 million ($3.28), from $692 million ($2.91) in the year earlier period. Sales rose to $26.3 billion from $25 billion.