CH-4 Diesel Guard

High-performance diesel engine oil for heavy-duty engines.

Commercial vehicle engine oils serve heavy-duty diesel engines in trucks, buses and construction machinery. These engines run long hours under high load with long drain intervals, so soot dispersancy, high-temperature oxidation resistance, shear stability and valvetrain wear protection are all more demanding. Diesel oils are classified by API C-series categories (CH-4, CI-4, CJ-4, CK-4 and so on), with newer categories setting tighter limits.

This page covers CH-4 Diesel Guard (Synthetic Diesel Engine Oil) — product code CH-4; category Automotive Lubricants / Commercial Vehicle Oils / Engine Oils; SAE 15W-40 / 10W-30; CH-4; pack 18L / 4L. The specification table below is taken from our product data as recorded, with no values estimated or filled in.

The table below reproduces the recorded product data; the notes that follow explain the classification and viscosity systems in general terms.

• SAE 15W-40 —— A multigrade viscosity grade: the number before the W rates low-temperature pumpability, where a smaller number means easier cold pumping and starting; the number after the W rates viscosity at 100 °C, where a larger number means a thicker film at high temperature (more sealing and wear margin) but also more flow resistance.One of the most widely used heavy-duty diesel grades: high viscosity at 100 °C and a strong oil film for long-haul, heavy-load and hot-ambient operation.
• SAE 10W-30 —— A multigrade viscosity grade: the number before the W rates low-temperature pumpability, where a smaller number means easier cold pumping and starting; the number after the W rates viscosity at 100 °C, where a larger number means a thicker film at high temperature (more sealing and wear margin) but also more flow resistance.Suited to moderate climates, commonly seen in earlier-generation engines and some diesel applications.
• API CH-4 is a heavy-duty diesel category from the earlier generation of API diesel specs, with defined requirements for soot dispersion, wear and high-temperature deposits; later categories (CI-4, CJ-4, CK-4) tightened these limits.
• 18L：Workshop and fleet size, suited to servicing several vehicles or a single commercial fill.
• 4L：A typical single-service volume for a passenger car.
• Grades and viscosities are stated on the product label and pack; the values listed here are exactly as recorded in our product data, and further technical documentation can be requested from our sales team.

This range contains 3 recorded variants (viscosity grade × packaging), listed below. The images in the gallery correspond to these variants and can be switched to inspect each pack.

• Maintains film strength under high load and high oil temperature, limiting liner, ring and bearing wear.
• Keeps combustion soot stably dispersed instead of letting it agglomerate into sludge or deposits.
• Resists high-temperature oxidation and mechanical shear so viscosity stays stable over longer drain intervals.
• Neutralises acids and provides alkalinity reserve for long-distance operation and higher-sulphur fuels.
• On vehicles with exhaust aftertreatment, helps manage the impact of ash, sulphur and phosphorus.

• Long-haul freight, cold-chain and tanker fleets.
• City buses and long-distance coaches.
• Continuous operation of construction, mining and port equipment.
• Vehicles built to stricter emission standards with exhaust aftertreatment, where the category requirement is higher.

The split from passenger car oils starts with the classification system itself (diesel C-series versus gasoline S-series) and continues with duty cycle: commercial oils typically carry higher alkalinity and tighter ash control for long drain intervals and aftertreatment compatibility, so a gasoline-only oil is not a substitute in heavy-duty diesel service.

• Follow the viscosity and performance grade specified in the vehicle or equipment manual; when several options are listed, choose according to ambient temperature and actual duty cycle.
• Manual gearboxes must use the specified fluid: gearboxes with brass or bronze synchronisers normally call for GL-4 or a dedicated manual transmission fluid rather than GL-5.
• Avoid long-term mixing of different brands or performance levels; prefer the same specification when topping up or changing fluid.
• Under sustained heavy load, frequent stop-start, hot or dusty conditions, shorten the drain interval and check fluid condition regularly.
• Replace filters where applicable during a fluid change and check the level and any leaks as specified.

• Product name and code: distinguishes different series built to the same specification (the recorded code is listed in the table above).
• Viscosity grade (SAE), e.g. 5W-30: rates low-temperature flow and high-temperature viscosity.
• Performance grade, e.g. API SP or ACEA A3/B4: the standard system and level the fluid meets.
• Net content and pack form, e.g. 4L or 18L: match it against the fill volume you need.
• Batch number and production date: for traceability and shelf-life checks.
• Manufacturer information and contact details: the reference point for any follow-up questions.

• Drain while the fluid is still warm for a more complete change, and have both a drain pan and a used-oil container ready.
• Replace the filter where applicable as the manual requires, and check that the sealing ring is intact.
• Use clean funnels and tools so that moisture, dust and debris do not enter the system.
• Fill to the volume the manual specifies and confirm the level on the dipstick or sight glass; transmission fluids usually need to be checked at a specified fluid temperature and by a set procedure.
• After the change, check the drain plug and mating surfaces for leaks, then re-check the level after a short run.
• Record the mileage or operating hours and the date so the next service can be scheduled.

• "Thicker is safer": only true within the range the manual allows — a viscosity that is too high raises flow resistance and can starve the engine during cold starts.
• "Dark oil means dead oil": diesel engine oil normally darkens as it disperses soot; decide on changes by mileage or hours and by oil analysis rather than colour.
• "The same grade from any brand can be mixed freely": emergency top-ups are understandable, but long-term mixing risks incompatible additive systems and can affect cleanliness and seals.
• "More oil is better": overfilling raises crankcase pressure and loads the oil separation system; fill to the dipstick mark.
• "A higher category always suits my engine": also check viscosity and the manufacturer approvals the manual calls for — some engines set specific limits on ash and phosphorus.

• Store in a cool, dry place away from direct sunlight and rain.
• Keep containers sealed against moisture, dust and contaminants, and use opened packs promptly.
• Keep production batch numbers on record and use stock on a first-in, first-out basis.
• Dispose of used oil and empty containers in line with local regulations to avoid soil and water contamination.

• Selection support: tell us the vehicle or equipment model, ambient temperature and duty cycle in your enquiry and we will point to the specifications we actually offer.
• Technical documentation: for more detailed product information, packaging or bulk supply, contact the sales team through the enquiry form and we will answer with what we have on file.
• Pack choice: the same specification often comes in several pack sizes — pick according to fill volume and stock turnover.
• Samples and volume: for bulk or long-term supply, include the quantity and delivery location in your enquiry.