Petrol prices have been rising in the west African country since October last year, when Obasanjo halted fuel subsidies and removed a price cap as part of a programme of economic reforms designed to kick-start the regional giant's stagnant economy.
Nigeria is the world's sixth largest exporter of crude, and with world oil prices at an all-time high, workers are in no mood to be told that they must tighten their belts and wait for prosperity to filter down to them.
"We are very determined. It's going fine," declared Owei Lakemfa, spokesman for the Nigeria Labour Congress (NLC), adding that the four-day "warning strike" would continue through Thursday as planned.
On Monday, Obasanjo attempted to draw the sting from the protest by inviting NLC president Adams Oshiomhole to join senior ministers on a new committee set up to look for ways to cushion the effect of fuel price risers on consumers.
But Oshiomhole remained defiant, saying he would accept nothing less than a return to the pump price of September 22, the day before petrol and diesel leapt 25 percent to around 55 naira (40 cents) per litre.
"The committee is a ploy. We are asking them to revert prices," Lakemfa told AFP.
NLC national mobilisation officer Denja Yacqub said that he would tour the commercial capital Lagos to check, but that the strike appeared to be solid.
Many businesses and government offices remained closed or semi-deserted in Lagos and other major cities, and public expressions of support for the strikers were many. But some people were returning to work.
Already on Monday, in the northern city of Kano and several regional centres, private sector businesses such as market traders and some transport had remained open.
On Tuesday, Kano's airport reopened, although schools and hospitals remained closed, and business was picking up in Lagos too.
"If I stay at home, how do my children feed? I am in full support of the NLC strike but I need to fend for my family too," said Abibat Oladimeji, a 32-year-old small trader in Lagos' normally teeming Balogun Street market.
"We market women support the NLC but if we are not here, how will the people eat?" asked 28-year-old Joke Akinlabi at the Oyingbo food market.
Nevertheless, the roads remained very quiet, banks and service stations closed, and the strikers appeared confident.
Flights at Lagos domestic terminal were disrupted as airlines grounded planes for lack of passengers, officials said.
International concerns over the work stoppage have focussed on Nigeria's oil industry, which exports around 2.5 million barrels per day.
Any disruption to supply could have global economic consequences with oil already surging to a record 54 dollars per barrel in London.
"There are great concerns about Nigeria. Though it is not affecting oil at the moment, people think it might," said oil trader Lee Elliot.
But labour leaders said the protest would not halt production.
"Our members are part of the strike. But as for oil production, skeletal operations are going on," conceded Elijah Okougbo, general secretary of NUPENG, the blue-collar oil workers' union.
And the general secretary of the white-collar oil union, PENGASSAN, Mojibayo Fadakinte, said: "The strike has not disrupted oil production and it will not. We have not asked our members to shut down oil production."
Spokesmen for Nigeria's foreign oil giants confirmed that exports had not yet been hit, but the Anglo-Dutch oil giant Shell warned that its production could suffer because of a leak and a fire on a major crude pipeline.
