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Castrol GTX Engine Oil

Castrol GTX is Castrol's everyday motor oil for petrol and diesel vehicles, with the 3X-Clean formula that fights engine sludge and helps extend engine life. Opie Oils stocks eight GTX grades, including 5W-30, the most common, in four specifications. Enter your registration in the Oil & Parts Finder to see the one your vehicle takes, or shop the range below.

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8 Products

Castrol GTX 15W-40 A3/B3 Mineral Engine Oil
Opie Price
£28.99
Price Beater
Castrol GTX 5W-30 RN17 Fully Synthetic Engine Oil
Opie Price
£44.95
Price Beater
Castrol GTX 10W-40 A3/B4 Part Synthetic Engine Oil
Opie Price
£34.99
Price Beater
Castrol GTX 5W-30 C4 Fully Synthetic Engine Oil
Opie Price
£45.95
Price Beater
Castrol GTX 0W-20 RN17 FE Fully Synthetic Engine Oil
Opie Price
£56.95
Price Beater
Castrol GTX 5W-30 A5/B5 Fully Synthetic Engine Oil
Opie Price
£39.95
Price Beater
Castrol GTX 0W-16 AN2022 Fully Synthetic Engine Oil
Opie Price
£50.95
Price Beater
Castrol GTX 5W-30 C2 Fully Synthetic Engine Oil
Free Shipping

20 Litres

Opie Price
£133.99
Price Beater

Searching by grade? Castrol GTX 5w30 comes in four specifications, so match the one your handbook lists. Castrol GTX 10w40 and Castrol GTX 15w40 suit older engines. Each product page lists every pack size and approval in full.

Need a C2 oil from stock? The GTX 5W-30 C2 is a special order in 20L only, but Castrol MAGNATEC 5W-30 C2 is in stock in 1L and 4L sizes.


GradeMeets or approved toTypeTypical use
0W-16 AN2022Renault AN2022, API SPFully syntheticRenault petrol engines from 2022, including 1.2 TCe mild and full hybrids
0W-20 RN17 FEACEA C5, Renault RN17 FEFully syntheticRenault engines that specify RN17 FE
5W-30 C2 (20L, special order)ACEA C2, PSA B71 2290Fully syntheticPeugeot, Citroen and other engines that specify C2
5W-30 C4ACEA C4, MB 226.51/229.51, Renault RN0720Fully syntheticRenault and Mercedes-Benz engines that specify C4
5W-30 A5/B5ACEA A5/B5, API SL, Ford WSS-M2C-913-A to DFully syntheticFord engines that specify 913-A to 913-D
5W-30 RN17ACEA C3, Renault RN17Fully syntheticRenault petrol and diesel engines that specify RN17
10W-40 A3/B4ACEA A3/B4, API SP, MB 226.5/229.3, VW 501 01/505 00, Renault RN0700/RN0710Synthetic technology (part synthetic)Older petrol and diesel engines that specify A3/B4
15W-40 A3/B3ACEA A3/B3, API SN, MB 229.1, VW 501 01/505 00MineralOlder, higher-mileage engines that specify A3/B3


Which Castrol GTX Grade Does Your Car Need

Your handbook gives two things: a viscosity grade, such as 5W-30 or 10W-40, and a specification or manufacturer approval, such as ACEA C3, VW 505 00 or Ford 913-C. Select a GTX that meets both. Two 5W-30 oils with different approvals are not interchangeable, and the wrong one can block a particulate filter or affect your warranty.

The quickest check is the Oil & Parts Finder, which selects the specification, grade and quantity for your vehicle's registration. For the background, see our engine oil viscosity guide and ACEA specifications guide, or ring 01209 202944 and we'll recommend one.

3X-Clean Sludge Protection

Sludge forms when oil breaks down under high temperatures, short trips and combustion contaminants, and the deposits restrict flow through the oilways. Castrol's 3X-Clean formula catches the particles, keeps them suspended and cleans existing deposits at each oil change, keeping engines cleaner for longer. In Castrol's own test, over four or more consecutive oil changes, GTX kept engines 35% cleaner than industry standards. The oil also resists thermal breakdown, so it holds its viscosity in stop-start driving.

Castrol GTX, MAGNATEC or EDGE?

Castrol's three car oil ranges suit different jobs. Match the approval in your handbook first, then choose the range.

  • GTX: everyday petrol and diesel cars on a standard service schedule, priced for routine servicing, with sludge protection for older and higher-mileage engines.
  • MAGNATEC: protection at start-up and warm-up, for cars that do a lot of cold starts and short journeys.
  • EDGE: Castrol's premium range for turbocharged and performance engines, or where the handbook calls for an approval only Edge meets.

Buying Castrol GTX from Opie Oils

  • UK's largest independent online retailer of oils and fluids, with over 100 brands and more than 1,500 car and bike oils and fluids in stock.
  • Free expert advice: ask the Opie experts for a recommendation.
  • Free UK delivery on orders over £80 (geographic restrictions apply).
  • 60-day returns and our No Leak Guarantee on every order.
  • Over 15,000 five-star reviews on reviews.io.

Questions and Answers

Is Castrol GTX fully synthetic?

It depends on the grade. The 0W-16, 0W-20 and all four 5W-30 oils are full synthetic, the 10W-40 A3/B4 is a synthetic technology part-synthetic oil, and the 15W-40 A3/B3 is a mineral oil.

What is Castrol GTX good for?

Everyday petrol and diesel cars on a standard service schedule, particularly older or higher-mileage engines where sludge is a risk. It isn't a racing oil, so check the approval your handbook asks for.

Can I use Castrol GTX in a diesel engine?

Yes, in the right grade. The 5W-30 C2, C4 and RN17 (ACEA C3) are low-SAPS oils suitable for diesels with a particulate filter. The 10W-40 A3/B4 and 15W-40 A3/B3 suit older diesels without one.

How often should I change Castrol GTX?

Follow the interval in your service schedule. The Oil & Parts Finder lists the interval and sump capacity for your registration.


Shop the full Castrol GTX range at Opie Oils today, with free UK delivery on orders over £80 (geographic restrictions apply) and our no-leak guarantee on every order.