Once on fire, always running in radio silence and nearly shunted into a wall with 15 laps to go, old man Bobby Unser, 47, won today's frightening Indianapolis 500 by five seconds over Mario Andretti -- or did he?

Andretti's team immediately filed a protest, saying Unser illegally passed four cars on the 150th lap when the field was running under a caution light. The United States Auto Club will hear the protest Monday morning.

Since the last death at Indianapolis in 1973, the 500 has been a relative picnic. Not today. If the 200-mph racers weren't bouncing off the walls today, they were on fire. If they weren't on fire, they were conking out in the oddest places. If cars lost, they protested (Andretti's teammate, Gordon Johncock, and A.J. Foyt joined the protest).

So bizarre were the goings-on that Unser even charged after the race that the pace car, of all things, about got him killed.

"The damned pace car (driven by former Indy raceer Duke Nalon) has got to get off the road," Unser said. "There was about to be the biggest crash you could imagine."

With 15 laps to go, the pace car led the field out of Turn 4 after a yellow-light (caution) period. Unser said the pace car dawdled so that slow cars up front clogged the straightaway ahead. At that point, Unser was the race leader and certain winner if he avoided the travail that had sent drivers Danny Ongais and Rick Mears to the hospital and turned a dozen $150,000 cars into junk.

To get clear of the traffic jam, Unser "took a gamble." He jerked his Penske-Cosworth hard left. What he was ahead then was not pleasant."I thought I was going to hit the pit wall head-on," he said. "One more car, and i'm history."

Instead of hitting anything, Unser passed the Sunday drivers. He also stole a large lead over Johncock, who up to that moment was locked on Unser's tailpipe. Then, with only six of the 200 laps on the 2 1/2-mile oval to go, Johncock's engine broke.

That left Andretti as the only one of 33 starters still in the same lap with Unser, and he was hopeless 14 seconds behind. Only Unser's victory-in-sight coasting made the margin anything less.

His third 500 victory made Unser the oldest winner by five years. Only A.J. Foyt, with four victories, has won more often, and Unser now joins his younger brother Al, Louis - Meyer, Mauri Rose and Johnny Rutherford as three-time winners. Unser averaged 139.084 mph in a race slowed by 11 yellow lights covering 69 laps. Fifteen cars finished, with Vern Schuppan third and rookies Kevin Cogan and Geoff Brabham next.

On a day when Unser didn't so much as see an accident and so would say, "The good Lord meant for me to win," there were two horrifying incidents that even reached out to touch some of the estimated 420,000 spectators here.

The first came on the 59th lap when Mears' car caught on fire during a pit stop. As the methynol fuel burned invisibly, the driver leaped from the car and his crewmen scattered. People in the grandstands 20 feet away scurried away from the heat, too, and speedway firemen smothered the fire in billowing white clouds of extinguisher.

Mear and three crewmen were treated for first- and second-degree burns at Methodist Hospital here. All were listed in good condition except for Derrick J. Walker, whose condition was serious.

Eight laps later, Ongais, who had led for three laps and was working his way back up after a pit stop, smashed into the wall in Turn 3. His car was ripped apart. It caught on fire. At least two spectators behind the wall seemed injured, but there was no confirmation of that. After surgery, Ongais is listed in "Fair-to-serious" condition at Methodist with a compound fracture of the right leg, a broken left forearm, chest injuries and possible internal injuries. A hospital spokesman said tonight that Ongais "will recover fully but it will be several months for total recovery."

Fire touched Unser, too, but he literally blew it out.

Even as firemen worked frantically around Mears' car, Unser made a pit stop in the space right next door. Both Mears and Unser run for owner Roger Penske. After taking on fuel, Unser pulled away -- and Penske said, "I saw the half-shaft burning." Fuel had been spilled and now was burning.

"I just heard a loud bang." Unser said, "and I felt a lot of heat. Sometimes if you keep going, you'll blow those things out. So I just gave it the gas."

With that fire gone, Unser, the pole-sitter at 200.546 mph and May's best runner here, said he worried only about four other drivers: Johnny Rutherford, Andretti, Johncock and A.J. Foyt.

Rutherford, last year's easy winner, conked out on the 25th lap when a cheap part broke on his fuel pump.

"I started hollering into the radio, 'Rutherford is out,'" Unser said. "And then I thought, 'What the hell am I doing on the radio?'" In four straight races now, Unser's pit-to-driver radio has malfunctioned. He relied on pit boards for instructions.

"I was happy Rutherford was out," Unser said. "It settled down to me, Johnnycock and Andretti. Foyt's engine was strong, but it turned out he wasn't handling well enough to be a factor."

On Lap 160, Unser was shocked.

Andretti passed him going into the first turn on a restart after a yellow.

"I said, 'Where'd he get all that speed? Man, they must have done somethin' to that dude,'" Unser said. "He couldn't catch me all day and here he goes around me. So I just reared up, milked the boost, gritted my teeth and got 'er wide open coming out of the second turn. And i passed him back. It wasn't easy, but at least I could do it."

That was Andretti's last charge, for he soon dropped far back, causing Unser to say into his dead radio, "Where'd Mario go?"

Where Andretti went, shortly after the finish, was to squawk that Unser violated the rule that forbids passing cars under a yellow light. If Unser is penalized a lap by the USAC, Andretti would become the winner and take the estimated $325,000 first prize.