The company, which employs around 6,000 staff on Wearside, has confirmed it is entering into consultations over closing its final salary pension scheme.
Around 1,500 workers at the plant would be affected if proposals to move them on to an alternative pension plan are approved.
The Japanese-owned car giant has said the consultation will continue over the summer and feedback from employees will help to shape its outcome.
On Saturday, more than 100 workers joined representatives from Unite the Union in holding a demonstration in the first rally held outside the plant since it opened in 1984.
Unite the Union has warned the changes have the potential to lead to the first industrial action at Nissan in Sunderland.
It is calling for a compensation package for the affected workers.
Steve Bush, national officer for Unite the Union, said: “The purpose of today’s march and rally is to send a clear message to the management of Nissan and Nissan Europe that they won’t be allowed to just take away the pension that has been built up over many years through the hard work and dedication of the workforce here.
“Their attitude towards the consultation has to shift significantly to have a compromise to allow us to negotiate and consult further down the line.”
Unite the Union said it will be meeting with the company for the first time in the coming week to discuss the changes as part of the consultation process.
Read more: Nissan worker speaks out and says he feels ‘betrayed’ over pension dispute
Kevin Raine, 54, who has worked at Nissan for 32 years, was due to retire next year but said he is now faces working an additional three years.
He said: “We are here to protest over the changes to the pension.
“I think it is disgraceful what they are doing.
“A pension is not a benefit, to me it’s people’s livelihoods, that’s what you sign up to Nissan for.
Craig McDonald, 50, who has worked at the plant for 31 years, said: “We want to work with Nissan, we want to work with the company to mitigate any changes that will have an impact on employees.”
Mark Adams, 55, who has worked at Nissan for 33 years, had been planning to retire imminently.
He said: “I was very disappointed.
“I have been a long term employee of 33 years, obviously you have got your goals and aspirations and things you want to do and things you expect, so to find out in the final furlong that things have changed is very disappointing.”
A Nissan spokesman said: “We are in close consultation with affected employees and their representatives as we try to resolve this together.
“The consultation will continue over the summer and feedback from employees is vital in helping to shape its outcome.
“We aim to provide competitive benefits to our highly valued staff, but these have to be balanced with the long term sustainability of our business.
“The level of company investment needed to maintain the defined benefit pension plan has grown to unsustainable levels.”