Farmers are calling for urgent action to address fuel filter blocking as issues begin to emerge again across the country.
Once again, farmers are facing problems linked to fuel with no sign of solutions to the issue since it was first raised in 2019.
Those affected say they are being left with the cost of repair, new filter replacements and vehicle down-time.
The specification and standards of fuel are being cited as the problem, NFU Scotland says, adding the introduction of improvements to fuel specifications have also been too slow.
When this problem first emerged 18 months ago, the union received more than 400 reports of filter blocking in Scotland alone.
This had cost some individuals 'thousands of pounds' in repair and replacement of parts and fuel treatments.
Joint lobbying work between NFU Scotland and NFU saw the Department of Transport and British Standards Institution (BSI) set up a taskforce, in which farming unions still participate to resolve the problems.
However, progress through the taskforce has been 'painfully slow', NFU Scotland says, as two years have past without a solution while blockages continue.
Jamie Smart, NFU Scotland’s Transport Advisor and representative on the taskforce, said 'urgent and focused action must be taken to address filter blocking'.
“The taskforce has had some small wins regarding changes to fuel specifications but getting those changes into the fuel supply chain have been delayed," he added.
“Testing of fuel samples has shown that most fuels reach current standards, however given that some fuel is still blocking filters and causing vehicle breakdowns, it is simply not fit for purpose.
“As a result, fuel filter blockages in tractors and motorised farm machinery remain a regular and costly problem for many Scottish farmers and crofters."
He urged farmers experiencing problems to check the fuel filter hub that NFU Scotland has created on its website for union members.