On January 2005, NASCAR made one of those announcements that elicits more yawns than headlines.

Then came last week’s racing at California Speedway. And suddenly, the topic of using unleaded fuel in NASCAR vehicles was burying the needle on the buzz-o-meter.

This week, in the wake of a California Nextel Cup race that featured a high number of blown engines, NASCAR observers are wondering about the effect of unleaded gasoline on the situation.

NASCAR traditionally has been exempt from provisions of the Clean Air Act of 1970, which mandated use of unleaded fuel in automobiles. But that did not mean that NASCAR was comfortable with its use of leaded gas.

During the years, NASCAR began testing alternative racing fuels, but none were deemed usable.

In 2004, NASCAR began testing an unleaded formula from Sunoco.

In January 2005, NASCAR announced that the fuel showed promise and would be used beginning with the 2008 season. A year and a half later, officials announced that the schedule for using unleaded fuel had been accelerated.

The fuel was first used in a Busch series race last July at Gateway International Raceway near St. Louis. A couple of other Busch and Truck series events featured the use of unleaded last year.

After analyzing the data from those races, officials announced that unleaded fuel would be put into use full time beginning with last weekend’s races at California.

In the days leading up to the race, several engine-builders talked about the potential effects of unleaded fuel on engines – and on racing.

Doug Yates, one of the most respected engine-builders in the garages, said the concern was lubrication. Leaded fuel, he said, has lubricating properties that unleaded does not.

“What we have problems with is valves and valve seats, and we’ve been through a very intense process of trying to find the right coatings to protect the valves from wear,” Yates said. “That’s one of the issues that we have, and hopefully have done our homework and we won’t have any problems with those.”

During the race, five cars retired because of what were listed as engine problems: one Ford, one Dodge, one Toyota and two Chevrolets.

The precise cause of the failures will not be known until the engines are taken apart and analyzed.

But Ken Schrader, who drives a Yates-powered Ford for the Wood Bros., said: “That’s very unusual for a Roush-Yates motor. They’re good, dependable engines. It could be a little bit of that (unleaded fuel).”

Jack Roush, owner of Roush Fenway Racing – whose driver, Matt Kenseth, won Sunday’s Auto Club 500 – went out of his way to praise the unleaded fuel after the race.

“I want to compliment Sunoco for this environmentally friendly, lead-free fuel that caused us no problem,” Roush said. “We didn’t have an issue with valve-seat recession or anything else that was a concern. From what I can see, the people that had trouble, it didn’t relate to the fuel. The fuel gave us good fuel mileage and it performed admirably.”

Yates said NASCAR needs to take the lead studying alternative fuels.

“Right now our whole country is in a bit of a crisis. What the people in the stands see, they go out and usually follow suit, so if we could be leaders in that way, I would be proud to be part of that.”