NEW YORK, JULY 6 -- American companies are less willing than they were a few years ago to dip into the corporate treasury to provide executives with a luxurious lifestyle, but many top managers still enjoy the use of corporate jets or other expensive benefits that are difficult to justify purely on business grounds, according to industry consultants and legal experts.

"I think a lot of these things are just play toys," said Graef S. Crystal, one of the nation's most prominent experts on executive compensation. "Even if the spending is for business, if it gets lavish enough, it seems to me that it crosses the line," said Crystal, a former consultant on executive compensation and now an adjunct professor at the the University of California at Berkeley.

The prickly issue of corporate perks came into the news this week when federal authorities filed civil charges against Thomas Spiegel, the former head of Columbia Savings and Loan of Beverly Hills, Calif., who allegedly squandered depositors' money on air travel, vacation homes and rock concert tickets.

Experts say such dramatic spending abuses by individual executives are the exception rather than the rule, particularly since tax law changes made it less appealing for companies to give them perquisites such as cars and low-cost loans.

Nevertheless, there is a large "gray area" where ego-driven managers frequently allow spending on their own comforts to overstep the bounds of expenses that can readily be explained as a legitimate cost of business, the specialists said. Such expenses absorb millions of dollars of funds each year, and yet are subject to little oversight by shareholders or tax authorities, they said.

"There's no way to trace how much abuse is going on," said Eric M. Ovsiew, deputy general counsel of Institutional Shareholders Services Inc., a consulting firm specializing in corporate governance issues. "As more is found, you don't know if there's more in existence or if you're a better watchdog. I have a feeling it's the latter."

Questionable expenditures include those for limousine service, luxurious private dining rooms and, perhaps most difficult to defend, corporate jets. Such benefits are justified to the shareholders and tax authorities as necessary to save the executive's time or to reduce stress.

Corporate spending to maintain a high-flying lifestyle picked up in the 1970s and early 1980s, particularly in some image-conscious industries like the savings and loan sector, analysts said.

"In the 1980s, it became important to some executives to live like the Sultan of Brunei, and this was true particularly in the S&L industry," said John Cuneo, general counsel of the National Association of Securities and Commercial Law Attorneys. His organization includes lawyers who represent shareholders who file suit against allegedly irresponsible corporate managers.

One of the worst apparent offenders among S&L executives was David L. Paul, who headed the failed CenTrust Savings Bank of Miami. He entertained politicians on a $7 million yacht, maintained at company expense, and used corporate funds to pay $13.2 million for a Rubens painting that he hung in his living room.

While most experts say that excesses have been particularly numerous in the savings and loan industry, some maintain that that sector merely has drawn an unusual amount of attention because of the collapse of many thrifts and the high cost of the government's rescue.

"I can't believe that the S&Ls are any more corrupt than anyone else," said Ovsiew.

Ovsiew, like other specialists, noted that improper or excessive corporate spending frequently becomes public only when a company has had economic or legal troubles that attract attention to it.

Certainly, there have been controversial cases outside the savings and loan industry. Armand Hammer, chairman of Occidental Petroleum Corp., infuriated many shareholders last year when the company revealed plans to spend as much as $150 million to build and endow an art museum to be named for him and to house his personal collection.

Ross Johnson, the former head of RJR Nabisco, achieved notoriety for his spending on a small fleet of corporate jets that he used to ferry around company directors, his friends in the sports world and even his dog.

Jets are the most frequently challenged perk because of their very high cost compared with the price of a first-class commercial ticket, analysts said. About 30 percent of companies that have private planes allow the chief executive officer to use them for personal purposes, although the executive usually is supposed to reimburse the company for such use, according to Mark H. Edwards, a principal in the management consulting firm of Sibson & Co.

According to surveys by Sibson of about 250 leading corporations, a tightening of tax rules has led to a reduction to 64 percent from 72 percent between 1985 and 1989 in companies that provide top executives with company cars. The share of companies offering low-cost loans to executives has fallen to 7 percent from 14 percent, while the fraction providing first-class air travel has risen to 33 percent from 29 percent.

While perks generally have been cut back, however, Sibson found that the pay of senior executives over the same five-year period rose nearly 40 percent.