Castrol RX Diesel 15W-40 is a premium quality mid-ash heavy duty diesel engine oil, great for plant, highway, off-road, and mixed fleet operations. RX DIesel contains cleaning agents to reduce harmful build-up on engines surfaces and pistons while also utilising anti-oxidant controls to prevent oil thickening over the service period to extended the life of your engine. This product can be used in turbocharged and naturally aspirated diesel engines requiring an oil meeting API CI-4 or earlier specification, and is particularly suitable for use in US engine technology pre ADR 80/02, such as Cummins, Mack, Caterpillar and Detroit Diesel (4-stroke) heavy duty diesel engines. Castrol RX Diesel 15W-40 is also suitable for use in diesel 4WDs and light commercial vehicles not fitted with DPFs (Diesel Particulate Filter) or DPDs (Diesel Particulate Diffuser). To find the oil type and viscosity suggested for your vehicle; either add your vehicle to My Garage or check with your manufacturer, vehicle user manual, your local mechanic or head in-store and talk to one of our friendly team.
Castrol RX Diesel 15W-40 is a premium quality mid-ash heavy duty diesel engine oil, great for plant, highway, off-road, and mixed fleet operations. RX DIesel contains cleaning agents to reduce harmful build-up on engines surfaces and pistons while also utilising anti-oxidant controls to prevent oil thickening over the service period to extended the life of your engine. This product can be used in turbocharged and naturally aspirated diesel engines requiring an oil meeting API CI-4 or earlier specification, and is particularly suitable for use in US engine technology pre ADR 80/02, such as Cummins, Mack, Caterpillar and Detroit Diesel (4-stroke) heavy duty diesel engines. Castrol RX Diesel 15W-40 is also suitable for use in diesel 4WDs and light commercial vehicles not fitted with DPFs (Diesel Particulate Filter) or DPDs (Diesel Particulate Diffuser). To find the oil type and viscosity suggested for your vehicle; either add your vehicle to My Garage or check with your manufacturer, vehicle user manual, your local mechanic or head in-store and talk to one of our friendly team.
Castrol RX Diesel 15W-40 CI-4/E7 20L 3418225
Castrol RX Diesel 15W-40 is a premium quality mid-ash heavy duty diesel engine oil, great for plant, highway, off-road, and mixed fleet operations. RX DIesel contains cleaning agents to reduce harmful build-up on engines surfaces and pistons while also utilising anti-oxidant controls to prevent oil thickening over the service period to extended the life of your engine. This product can be used in turbocharged and naturally aspirated diesel engines requiring an oil meeting API CI-4 or earlier specification, and is particularly suitable for use in US engine technology pre ADR 80/02, such as Cummins, Mack, Caterpillar and Detroit Diesel (4-stroke) heavy duty diesel engines. Castrol RX Diesel 15W-40 is also suitable for use in diesel 4WDs and light commercial vehicles not fitted with DPFs (Diesel Particulate Filter) or DPDs (Diesel Particulate Diffuser). To find the oil type and viscosity suggested for your vehicle; either add your vehicle to My Garage or check with your manufacturer, vehicle user manual, your local mechanic or head in-store and talk to one of our friendly team.
Castrol RX Diesel 15W-40 is a premium quality mid-ash heavy duty diesel engine oil, great for plant, highway, off-road, and mixed fleet operations. RX DIesel contains cleaning agents to reduce harmful build-up on engines surfaces and pistons while also utilising anti-oxidant controls to prevent oil thickening over the service period to extended the life of your engine. This product can be used in turbocharged and naturally aspirated diesel engines requiring an oil meeting API CI-4 or earlier specification, and is particularly suitable for use in US engine technology pre ADR 80/02, such as Cummins, Mack, Caterpillar and Detroit Diesel (4-stroke) heavy duty diesel engines. Castrol RX Diesel 15W-40 is also suitable for use in diesel 4WDs and light commercial vehicles not fitted with DPFs (Diesel Particulate Filter) or DPDs (Diesel Particulate Diffuser). To find the oil type and viscosity suggested for your vehicle; either add your vehicle to My Garage or check with your manufacturer, vehicle user manual, your local mechanic or head in-store and talk to one of our friendly team.
in 4 offers
The lowest price for Castrol RX Diesel 15W-40 CI-4/E7 20L 3418225 right now is $153.85 at sparesbox.com.au, compared across 4 retailers.
The all-time low was $101.99 on 23 Nov 2025 — today's price is 51% above the lowest ever. It has been notably cheaper before — worth setting a price alert.
Prices last updated 3 June 2026.
Last updated at 03/06/2026 22:38:47
Castrol RX Diesel 15W-40 CI-4/E7 Engine Oil 20L 3418225 fits TOYOTA DYNA 250 3.7 D (BU211, BU221), 4.1 D (BU212, BU222), 4.6 D (XZU307), 4.6 TDi (X...
Delivery between 9–17 June $9.90
Castrol RX Diesel 15W40 Engine Oil CI-4/E7 20L 3418225 fits Toyota Land Cruiser Prado 3.0 TD (KZJ95) 1KZ-TE AWD Diesel SUV 03/00-02/03 96kw
Delivery between 4–16 June $10.95
Castrol Rx 15W-40 Ci-4 E7 Diesel Engine Oil 20L, 3418225
Delivery between 10–12 June $15
Castrol RX Diesel 15W-40 CI-4/E7 Engine Oil, 20 Litre
Delivery between 8–11 June $20
originally posted on supercheapauto.com.au
I'll have to stop shopping at Supercheap as a matter of course & start shopping around. Repco is $15 cheaper, Supercheap is not super cheap. Maybe SC should pull their finger out & monitor their opposition's prices & start living up to their name. It might be only $15 in this case (actually $30 as I purchased 40 litres) but enough for this customer to no longer use SC as my 'default' supplier of auto supplies. The oil is as good as any other top brand oil of the same specs.
originally posted on supercheapauto.com.au
I drive a 2004 landcruiser ute factory turbo with close to 450k on the clock. I am no expert on oils but for all intents and purposes this oil does a great job. I find it stays in pretty good nick up to my 5000km service interval, doesnt go super black or smell burnt. No engine noises/tapping etc. Always a plus when its on salefor around the $90 mark.
originally posted on repco.com.au
I’ve used this in my Kubota 15kva genset since new and changed the oil every 200 hours. Genset is now approaching 10,000 hours and still runs and sounds like new some 5 years on. Thinking I should easily get the estimated 20,000 hours from it thanks to this good oil at a price that enables regular changing a little before actually due!
| Oil Composition | Mineral Oil |
| ACEA | ACEA E7 |
| API | CI-4 / SL |
| CAT | ECF-2 |
Castrol RX Diesel 15W-40 CI-4/E7 Engine Oil 20L 3418225 fits TOYOTA DYNA 250 3.7 D (BU211, BU221), 4.1 D (BU212, BU222), 4.6 D (XZU307), 4.6 TDi (X...
Delivery between 9–17 June $9.90
Castrol RX Diesel 15W40 Engine Oil CI-4/E7 20L 3418225 fits Toyota Land Cruiser Prado 3.0 TD (KZJ95) 1KZ-TE AWD Diesel SUV 03/00-02/03 96kw
Delivery between 4–16 June $10.95
Castrol Rx 15W-40 Ci-4 E7 Diesel Engine Oil 20L, 3418225
Delivery between 10–12 June $15
Castrol RX Diesel 15W-40 CI-4/E7 Engine Oil, 20 Litre
Delivery between 8–11 June $20
I'll have to stop shopping at Supercheap as a matter of course & start shopping around. Repco is $15 cheaper, Supercheap is not super cheap. Maybe SC should pull their finger out & monitor their opposition's prices & start living up to their name. It might be only $15 in this case (actually $30 as I purchased 40 litres) but enough for this customer to no longer use SC as my 'default' supplier of auto supplies. The oil is as good as any other top brand oil of the same specs.
I drive a 2004 landcruiser ute factory turbo with close to 450k on the clock. I am no expert on oils but for all intents and purposes this oil does a great job. I find it stays in pretty good nick up to my 5000km service interval, doesnt go super black or smell burnt. No engine noises/tapping etc. Always a plus when its on salefor around the $90 mark.
I’ve used this in my Kubota 15kva genset since new and changed the oil every 200 hours. Genset is now approaching 10,000 hours and still runs and sounds like new some 5 years on. Thinking I should easily get the estimated 20,000 hours from it thanks to this good oil at a price that enables regular changing a little before actually due!
Due to ever changing oil grades this is better for Golf Carts as it has less fumes behind when driving. Not a big fan of RX Super on old H series Landcruisers as the fumes behind are so bad.
Been using RX Super for years and it has done really well. Recently changed over to RX Diesel Oil on the recommendations of Castrol because it suited my vehicles engine better. So far, it too, has been fine.
After running thicker oils to quieten the old donk down. This oil for a 15w-40 exceeded my expectations I didn't think oils were all that different but this is great value and an even better product. Very happy
Placed the order for Castrol RX Diesel Engine Oil 15W-40, 2x20L. Price was excellent value. Processing of payment was efficient. Received updates of the status of the order re receipt of order, dispatch of order and delivery was within a very short periond of time. In all, a smooth, stress free purchase that left me very happy to do it again.
I am using this in a 10 year old NA diesel tractor with mechanical fuel system. This product was chosen for its proven reliability and quality at an affordable price.
I have been using this oil on a small Hino Tipper since Castrol replaced the RX Plus. The Motor has done nearly 400,000km now and still not using oil. I guess that speaks for itself. However, I do change the oil a bit sooner than recommended.
After hours of research for an oil that would be the best for my old marine engine that would not cost me an arm and a leg i settled on Castrol RX Diesel oil at a fantastic price from Supercheap and delivered to my door. I took up the four payment option which helps my budget owning a boat. Great service and product the old engine runs smoother and quieter.
| Oil Composition | Mineral Oil |
| ACEA | ACEA E7 |
| API | CI-4 / SL |
| CAT | ECF-2 |
