Moral renovation in Mexico?

Longstanding familiarity and dependence often spark a proliferation of names for the same concept. Just as the nomadic Somalis have 45 separate words to identify the camel because of the dromedary's importance in their lives, Mexicans have coined dozens of synonyms for corruption, a curse that afflicts their political system, exacerbates a ''come back tomorrow'' bureaucracy, and diverts critical resources from an acutely depresssed and debt-ridden economy.

Cohecho (bribe); mordida (payoff); vendeplaza (job selling); soborno (graft); igualas (covert payments to reporters); and aviador (person paid without working) - these words form part of Mexico's thick dictionary of corrupt practices.

Aware of this lexicon and the acts that inspire it, each new Mexican president pledges to launch a no-holds-barred attack on wrongdoing. Sanctimonious speechmaking eventually gives way to the prosecution of several conniving, middle-level officials. The government-manipulated press flogs them for a few weeks; a politically sensitive judge convicts them of embezzlement; the malefactors pay back the ill-gotten funds; and the culture of corruption remains intact. In fact, upon completing six-year terms, chief executives typically retire in affluence far beyond their modest government pensions.

Miguel de la Madrid, Mexico's Harvard-educated President, who took office a year ago, appears to have broken with tradition. In keeping with his commitment to ''moral renovation,'' a theme trumpeted from Chihuahua to Quintana Roo during his election campaign, he has begun cracking down on the centerpiece of Mexican corruption, its oil industry.

A late-1970s boom generated fortunes that would excite the envy of Croesus. Many entrepreneurs fattened their bank accounts legally. Yet, talk of corruption and tainted wealth embroils everyone, from the drilling equipment supplier expected to pay a kickback to purchasing agents at Pemex, the state oil monopoly , to the taxpayer incensed by ex-President Jose Lopez Portillo moving into a posh, five-home compound on 71/2 acres outside the capital.

''It doesn't matter if they steal a bit,'' said a taxi driver accustomed to forking over mordidas to policemen for real or fictitious traffic violations, ''but they shouldn't steal so much.''

Not only were funds wasted both in drilling redundant wells near Poza Rica and on laying an unnecessary $1.5 billion pipeline from the Isthmus of Tehuantepec to Texas, but the Lopez Portillo administration squandered millions of dollars in erecting a skyscraper at Pemex's headquarters when four or five smaller buildings could have been constructed at a fraction of the cost.

Of course, every project generates ''commission'' and jobs, many of which are sold by union leaders. Then there is the little matter of what happened to 317 million barrels of Mexico's oil between 1976 and 1982. Pemex and other official agencies can't account for it.

De la Madrid's attorney general first brought charges against several former Pemex managers, and cynics thought that would be the last heard of moral renovation. Yet, in June authorities accused Sen. Jorge Diaz Serrano, former head of Pemex and architect of Mexico's oil boom, of taking part in a $34 million fraud in connection with the purchase of two Belgian natural gas tankers. Congress stripped him of his legislative immunity, and the oilman-turned-politician - assigned No. 666 - insists upon his innocence while awaiting trial in the capital's Reclusorio Sur prison.

Why did de la Madrid go after a ''big fish,'' as Mexico City journalists call Diaz Serrano, instead of minnows? Why has he undertaken the anticorruption fight when prospects for success appear so slim because of the ubiquitous presence of malfeasance?

To begin with, he wants to distance himself from the obscene corruption of his predecessor's term, while using the Diaz Serrano affair to deflect public attention from stern belt-tightening measures designed to pull the nation of 75 million inhabitants from the brink of bankruptcy.

Prosecuting a bigshot like Diaz Serrano may also demonstrate that the elite cannot enrich itself unjustly when sacrifices are being demanded of both the angry, hard-pressed middle class and the masses who live in hardscrabble poverty.

Above all, de la Madrid wants to make the former Pemex chief an example for ambitious politicians; to let them know that illegal actions - at least blatant ones - will incur his wrath and spike their chances for a governorship, a cabinet post, or - most important - the presidency.

De la Madrid's is a daunting task, but a few formerly dust-covered words - cautela (caution), responsibilidad (responsibility), cuidado (care) and vigilencia (vigilance) once again enjoy currency in the ancient Aztec capital.