Heavy Duty & Fleet
Heavy-duty diesel oil does a harder job than any car oil. It has to carry soot without thickening, neutralise the acids that higher-sulphur fuel produces, and hold oil…
Formulated to meet
API CI-4/SLACEA E7API SLAPI GL-5API GL-4ISO VG 10 / 46 / 68DOT 4ASTM D3306 & BS 658001 / Overview
Heavy-duty diesel oil does a harder job than any car oil. It has to carry soot without thickening, neutralise the acids that higher-sulphur fuel produces, and hold oil pressure in an engine that spends hours at full load on a gradient.
The truck and bus range is 15W-40 to API CI-4: ULTRA PLUS, which also carries API SL and ACEA E7 for mixed fleets, and DIESEL ENGINE OIL for high-speed, high-load running. An engine specified for API CK-4 needs a CK-4 oil — CI-4 is the previous category and is not a substitute where a particulate filter is fitted. We will tell you that rather than sell you the nearest thing.
Every batch is released by AG Lubricants FZE against a certificate of analysis, with a retained sample kept on file so any pack in the field can be traced back. How it is tested
02 / The range
Heavy Duty & Fleet
Super high-performance diesel engine oil incorporating new-generation additive technology. State-of-the-art dispersancy gives greatly improved soot handling and optimised protection for critical components such as the valve train, in on-highway and off-highway vehicles.
Heavy Duty & Fleet
Heavy-duty diesel engine oil for high-speed and heavy-load operation. Controls soot and keeps engines clean, with high thermal stability, oxidation resistance and good low-temperature flow for easy starting.
03 / Questions
A 20W-50 API CI-4 remains the most widely used grade for older engines running that route, because it holds oil pressure when hot and tolerates variable fuel quality. Modern engines with a particulate filter need API CK-4 — typically a 15W-40 — because CK-4 limits the ash that blocks a filter.
CK-4 is the current heavy-duty category. It carries more soot before viscosity climbs, resists oxidation better under sustained load, and limits ash, phosphorus and sulphur to protect aftertreatment. CI-4 is older and still perfectly valid for engines without a particulate filter. CK-4 is backward compatible; CI-4 is not forward compatible.
Most modern and mid-age sets take a multigrade diesel oil such as a 20W-50. Older sets are often specified for a straight SAE 40 or SAE 50, and run best on one because there is no viscosity modifier to shear down at constant load and temperature.
No. Passenger car oils are formulated for a different acid load, soot load and additive limit. Running one in a heavy-duty diesel engine will shorten the drain interval dramatically and can cause bore polishing and ring sticking.
04 / Before you buy
Why dust, long gradients and short journeys make ordinary local driving count as severe service.
What the two numbers on an oil pack mean, and why a thicker oil is not the safer choice.
How to read an API or ACEA performance level, and which part of it your machine actually needs.
05 / Other families
Send us the machines you run and the volumes you need. Our technical team will confirm the grade, the pack size and an indicative price — usually within one working day.
