So far, the United Steelworkers work-stoppage has been ordered at only nine plants across the country,
"If something doesn't break free, it will spread" warned Jim Payne, of USW Local 5 in Martinez.
The national union has operations and maintenance members at more than two hundred refineries, which produce about two-thirds of domestic fuel.
"National was willing to keep talking past midnight Sunday, but the industry refused, and left the table, and so we had no option," Payne told KTVU, at the union hall where dozens of picket signs are stacked and ready to be assembled.
Outside the Tesoro plant, some workers, but not all, were being turned away as they arrived for their night shifts.
"I just went up to the gate and they said 'go home, " complained Daryl Brooks of Vallejo, who works for a safety contractor doing maintenance work at the refinery.
"I was watching the Super bowl, and left the game to get here, just to go back home," Brooks told KTVU.
Picket lines are already up in Houston, and planned for plants in Washington and Kentucky, as well.
Tesoro's shutdown is gradual, a timetable mutually agreed to by the union and management, that will proceed until at least mid-day Thursday Feb. 5.
"It's a very complex operation, some units are more complex than others, they'll take longer to shut down, and some have to be shut down in sequence," explained Payne.
It's the first strike against refineries since 1980, and the union says it's about more than money: they're concerned about working conditions, safety, understaffing, and fatigue.
The Tesoro facility will continue to operate as a terminal during the strike, taking in product and shipping out, but not producing.
Currently, it's midway through a "turnaround", a rigorous maintenance upgrade, so it's running at about half capacity anyway.
"We need to finish up our job," contractor Hector Palacios told KTVU, one of 1200 outside contractors who are part of the safety project.
Palacios traveled from Texas to work on the turnaround, and now he and many others are in limbo because the strike idles them too.
"I want to get in there and earn that money, " he said ruefully, "we've come a long way, we want to finish it up, go home, and get on to the next one."
Tesoro management told KTVU it would not have any immediate comment on the labor dispute.
If the USW national union widens the strike, it could affect the Bay Area's other big refineries: Shell Oil in Martinez and Chevron in Richmond.
Those facilities have indicated they will remain operating in a strike, using replacement and management workers, something the union criticizes as unwise and unsafe.