NEW YORK, JULY 20 -- Opening a new front in its bitter legal war against Texaco Inc., Pennzoil Co. today proposed a bankruptcy reorganization plan for Texaco under which Pennzoil would accept $4.1 billion to settle their three-year-old dispute over a merger contract.

But sources close to the case said today that Texaco is contemplating its own unusual reorganization plan under which Pennzoil might eventually be paid not in cash, but in barrels of oil.

In an unexpected twist, the sources also said that Texaco is considering using an arcane theory about the value of oil, which was presented by Pennzoil at its 1985 trial against Texaco, to calculate the appropriate amount of oil that might be paid to Pennzoil. If Texaco succeeded with that plan, it might reduce by billions of dollars the cash value of its liability to Pennzoil.

Ending weeks of public silence, Pennzoil today renewed its attacks on Texaco and said its $4.1 billion reorganization plan was necessary because Texaco management faced "obvious conflicts of interest" and "appears to be acting to entrench its self-interest at the expense of Texaco's creditors and shareholders."

Texaco declined any comment.

Under the plan proposed by Pennzoil today, Texaco would emerge from bankruptcy after paying all of its creditors except Pennzoil in full, including interest. Pennzoil would receive $4.1 billion, plus interest, to settle its outstanding $10.3 billion legal judgment against Texaco.

Pennzoil was awarded a record verdict in November 1985 when a Houston jury found that Texaco had improperly interfered with a merger contract between Pennzoil and Getty Oil Co.

Texaco appealed, but earlier this year the Texas Court of Appeals upheld all but $2 billion of the jury's award.

On April 12, citing financial pressures caused by the Pennzoil judgment, Texaco sought protection from its creditors under the federal bankruptcy laws. It has appealed the Pennzoil judgment to the Texas Supreme Court.

The plan proposed by Pennzoil would require the approval of Texaco's creditors, shareholders and federal bankruptcy Judge Howard Schwartzberg, who is presiding over the bankruptcy proceedings in White Plains, N.Y.

Pennzoil said its proposal would be withdrawn unless Schwartzberg denies by Aug. 11 a motion by Texaco to extend until 1988 the period in which Texaco has exclusive rights to file a bankruptcy reorganization plan.

Schwartzberg has scheduled oral arguments on Texaco's motion for Thursday and is expected to rule by the end of this week.

The viability of Pennzoil's proposed reorganization and settlement depends not only on Schwartzberg's ruling, but on the receptiveness of other creditors, including banks, bondholders and rival oil companies, to the plan -- particularly to the $4.1 billion settlement amount Pennzoil has suggested.

Sources close to the case said that Pennzoil has been circulating its proposed reorganization plan among creditors for several weeks and that it has not met with an enthusiastic reception. One source said that a group of creditors expressly rejected the $4.1 billion figure two weeks ago.

Baine Kerr, chairman of Pennzoil's executive committee, said in an interview that he did not know how the creditors would respond now that the proposal has been filed publicly.

"Everybody would like to see us take as little as possible," Kerr acknowledged. "There's going to be a lot of people who would like to see us reduce our claim. But we've got a responsibility to our own people."

Texaco is working hard behind the scenes to persuade creditors that its own reorganization plan, still in the drafting stages, will treat them more favorably than any proposed by Pennzoil.

Sources close to the case said that Texaco is developing an unusual plan under which Pennzoil's claim would be treated separately from all other creditors. The sources said that Texaco is considering a reorganization proposal that would establish an independent escrow account from which Pennzoil would be paid "in kind" -- that is, with oil and natural gas -- if its judgment is upheld on appeal.

The sources said that the plan contemplated by Texaco, if approved by Schwartzberg and upheld on appeal, would depend, ironically, on damage theories presented by Pennzoil at trial. Texaco has repeatedly criticized those theories, which rely on long-term projections of drilling costs and oil prices, as overblown and farfetched.

If Texaco used those theories to calculate the amount of oil it owed Pennzoil, it might reduce by billions of dollars the present value of any assets it had to transfer to Pennzoil.

The amount of oil to be transferred would be calculated not by its current price in the marketplace, but by a complex formula describing long-term oil replacement costs.

If such a bankruptcy reorganization plan is put forward by Texaco, it is certain to be opposed vehemently by Pennzoil.

That opposition would likely set off a new round of appeals in the federal courts, further postponing a final outcome of the case.