Kenyan motorists are facing new risks after the government temporarily waived fuel sulfur standards, a move experts and vehicle owners say is meant to stabilize fuel supply, but which experts warn could damage vehicles and raise long-term costs.
The waiver, announced on April 30, allows petrol and diesel sold in the country to contain up to 50 milligrams of sulfur per kilogram, up from the 10 milligrams per kilogram limit that had just been introduced under new fuel quality rules.
The government says the decision will be in place for six months and was driven by global fuel supply disruptions linked to conflict in the Middle East and challenges along key shipping routes.
While the move is expected to ease pressure on fuel imports and help prevent shortages, mechanics, environmental experts, and automotive industry players say the decision exposes vehicle owners to serious mechanical and financial risks, especially for those driving newer cars.
How Higher Sulfur Fuel Affects Your Engine
Sulfur is a naturally occurring element found in crude oil and cannot be completely removed during the refining process.
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However, when fuel with higher sulfur levels is burned inside an engine, it produces sulfur dioxide and sulfur trioxide.
These gases can combine with water vapor during combustion to form sulfuric acid, a highly corrosive substance.
Mechanics explain that sulfuric acid gradually eats away at critical engine components such as piston rings, bearings, and valve systems.
Over time, this corrosion weakens the engine, reduces efficiency, and shortens its lifespan.
The problem is bigger when sulfuric acid contaminates engine oil, breaking down additives that protect the engine from wear, heat, and corrosion.
“Sulfuric acid is a highly corrosive substance, and it has very detrimental effects on the engine. What does it result in? Excessive corrosion of the engine parts. I am talking about the piston rings, the bearings and the valve train over time,” Joan Nyambura, an automotive expert from 4Real warned.
As a result, engine oil deteriorates faster, compromising lubrication and cooling. Mechanics say drivers may be forced to service their vehicles more frequently to avoid serious damage, increasing routine maintenance costs.
Diesel vehicles are considered the most vulnerable.
In Diesel engines, higher sulfur content leads to the formation of sulfates, which turn into ash.
This ash can clog emission control systems, including diesel particulate filters, exhaust gas recirculation systems, and selective catalytic reduction units.
Once clogged, these systems reduce engine power, increase fuel consumption, and raise emission levels.
The danger, mechanics warn, is that damage does not happen overnight.
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Vehicles may continue to run normally for weeks or months before symptoms such as warning lights, reduced power, or increased fuel consumption appear, by which time repairs can be costly.
Why modern cars face higher risks
Modern vehicles, especially Euro 5 and Euro 6 models commonly imported from Japan and Europe, are designed to run on ultra-low sulfur fuel.
Manufacturers globally treat fuel quality and emission systems as a single package, meaning changes in fuel standards directly affect how these systems perform.
Automotive experts say higher-sulfur fuel can poison catalytic converters and other emission-control components, reducing their effectiveness.
In some cases, the damage may be partially reversible if the vehicle later switches back to cleaner fuel, but prolonged exposure increases the risk of permanent failure.
Replacing parts such as catalytic converters, diesel particulate filters, or sensors can cost vehicle owners tens of thousands, or even hundreds of thousands, of shillings.
The experts also warn that using fuel outside manufacturer specifications could lead to warranty disputes, leaving owners to bear repair costs on their own.
Some mechanics advise motorists to shorten oil change intervals by up to 30 percent and use high-quality engine oils with stronger protective additives to reduce acid damage.
However, these measures raise running costs at a time when motorists are already struggling with high fuel prices and the cost of living.
Beyond vehicle damage, higher sulfur fuel raises environmental and public health concerns.
Burning sulfur-rich fuel increases sulfur dioxide emissions, worsening air pollution and increasing the risk of respiratory illnesses, especially in cities with heavy traffic.
The waiver has also revived public anxiety following recent revelations that substandard fuel had already entered the market earlier in the year, leaving motorists uncertain about the quality of fuel they have been using.
