DETROIT — Keep it short. A strike that lasts more than a few days could do irreparable damage to GM as it launches three key vehicles.

The acclaimed Buick Enclave and Cadillac CTS and the upcoming Chevrolet Malibu could all be jeopardized, and the brands that sell them might not recover.

It's an article of faith for some people within General Motors Corp. that the company's last protracted strike — a 54-day slugfest in 1998 — drove the last nail into Oldsmobile's coffin. The brand had just begun a major push to sell its Intrigue midsize sedan, a very good car that many observers thought was a match for the Toyota Camry when it went on sale as a 1998 model.

The shutdown at a key components plant in Flint stalled the Intrigue's momentum. The car never recovered, and GM killed Oldsmobile just more than two years later.

The situation for Buick is nearly identical. It's a troubled brand with a distinguished history. GM executives have publicly mulled shutting it down if there's no progress from new models like the Enclave, which went on sale this spring.

The graceful and luxurious Enclave is hot right now, challenging established models like the Lexus RX350.

Take the pot off the boil for long, and GM and the UAW risk spoiling the soup.

September always is a crucial time for automakers. They gear years of strategy around the fall production and advertising launch of new models. That's why contracts expire now: to give the UAW maximum leverage.

GM's embryonic recovery makes it especially vulnerable this year. The company's plans for Buick, Cadillac and Chevrolet hinge on the Enclave, CTS and Malibu.

"GM can probably withstand 10 days without losing much of a beat," said Jim Hall, vice president for industry analysis in the Southfield, Mich., office of consultant AutoPacific. A short strike shouldn't hurt the crucial new models' sales or the image, he said.

A long strike is another matter. "It can be crippling to a car," Hall said. "Once you start advertising, you have to have something to sell."

The money to promote the vehicles is already spent, and the ads are scheduled. GM can't postpone them, and it will have other vehicles it needs to advertise by the time a long stoppage ends.