Castrol GTX ULTRACLEAN 5W-30 Motor Oil
API SQ Synthetic Blend 5W-30 Motor Oil with Advanced Sludge Protection
Castrol GTX ULTRACLEAN 5W-30 is a synthetic blend motor oil formulated to help protect gasoline engines from sludge, high-temperature deposits, wear and viscosity breakdown.
The current formulation meets API SQ and ILSAC GF-7 performance requirements and is designed for vehicles where the manufacturer specifies SAE 5W-30 and compatible gasoline-engine oil standards.
Castrol's current GTX ULTRACLEAN formulation uses its 3X Protect approach to address three common contributors to engine sludge: heat, contaminants and frequent short trips. It is formulated to help clean existing sludge while creating a barrier that helps reduce new deposit formation.
Key Benefits
- SAE 5W-30 synthetic blend motor oil
- Meets current API SQ performance requirements
- Meets ILSAC GF-7
- Helps clean existing engine sludge
- Helps protect against new sludge formation
- 1.4X cleaner than the API SQ Sequence VH industry standard
- Helps protect against high-temperature deposits
- Provides protection against viscosity breakdown
- Provides protection against thermal breakdown
- Premium-quality base oils
- Anti-wear additives help protect critical engine components
- Suitable for gasoline engines requiring SAE 5W-30
- Meets Ford WSS-M2C946-B1
- Meets Ford WSS-M2C961-A1
- Meets engine-test performance requirements of Chrysler MS-6395
- Backward compatible with applicable earlier API and ILSAC gasoline-engine categories where SAE 5W-30 is specified
Current API SQ and ILSAC GF-7 Performance
The current Castrol Product Data Sheet lists:
- API SQ
- ILSAC GF-7
- Ford WSS-M2C946-B1
- Ford WSS-M2C961-A1
- Meets engine-test performance of Chrysler MS-6395
Castrol's current U.S. product information also identifies GTX 5W-30 as meeting or exceeding:
- API SQ
- API SP
- API SN PLUS
- API SN
- ILSAC GF-7
This gives the current formulation backward compatibility with many earlier gasoline-engine API categories, provided SAE 5W-30 is the correct viscosity and no additional manufacturer-specific approval is required.
3X Protect Sludge Control
Engine sludge is a thick deposit that can form when engine oil is exposed to difficult operating conditions.
Castrol identifies three common contributors:
- Heat
- Contaminants
- Frequent short trips
Its current GTX 3X Protect formulation is designed to help clean away existing sludge while creating a barrier that helps reduce new deposit formation.
Keeping oil passages cleaner helps the lubricant circulate properly and reach critical engine components.
1.4X Sludge Protection
The current Castrol GTX ULTRACLEAN 5W-30 Product Data Sheet states that the formulation is:
1.4X cleaner than the industry standard
based on the API SQ Sequence VH sludge test.
This replaces the older 45% cleaner than API SN PLUS language found in PSC's previous Product Data Sheet.
The test result is a comparative laboratory performance claim and should not be interpreted as a guarantee that every engine will be cleaned to the same degree.
What Does 5W-30 Mean?
5W
The 5W rating describes the oil's low-temperature characteristics. It is designed to flow and circulate during cold starts within the requirements of an SAE 5W grade.
30
The SAE 30 portion describes viscosity at normal engine operating temperature.
This combination makes 5W-30 suitable for a broad range of gasoline engines where the vehicle manufacturer specifies the grade.
Do not substitute SAE 5W-30 for another viscosity solely because it is widely used. Follow the vehicle manufacturer's recommendation.
Synthetic Blend Motor Oil
Castrol GTX ULTRACLEAN 5W-30 is marketed in the U.S. as a synthetic blend motor oil.
Synthetic blend formulations combine conventional and synthetic base-oil technology with an additive package designed to provide characteristics such as:
- Sludge control
- Deposit protection
- Oxidation resistance
- Anti-wear protection
- Viscosity stability
- Low-temperature performance
Whether a synthetic blend is appropriate depends on the engine's required viscosity and performance specification.
High-Temperature Deposit Protection
High engine temperatures can accelerate oil oxidation and contribute to deposits on internal components.
GTX ULTRACLEAN is formulated to provide protection against high-temperature deposits while helping maintain engine cleanliness throughout the recommended oil-change interval.
This can be particularly relevant in driving conditions involving:
- Heavy traffic
- Stop-and-go operation
- High ambient temperatures
- Frequent short trips
- Extended engine operation
Protection Against Viscosity and Thermal Breakdown
Motor oil is exposed to heat and mechanical stress every time an engine operates.
Over time, those conditions can affect viscosity and reduce the oil's ability to maintain a protective film.
Castrol GTX ULTRACLEAN 5W-30 is formulated to resist viscosity and thermal breakdown, helping maintain lubrication of moving engine components during the service interval.
Ford Applications
The current Castrol information lists GTX ULTRACLEAN 5W-30 as meeting:
- Ford WSS-M2C946-B1
- Ford WSS-M2C961-A1
Always confirm the exact Ford specification listed for the engine before use.
Chrysler MS-6395
The current Product Data Sheet states that Castrol GTX ULTRACLEAN 5W-30 meets engine-test performance of Chrysler MS-6395.
This wording should be preserved rather than describing the product as formally approved unless Castrol provides a specific approval statement.
Gasoline Engine Applications
Castrol GTX ULTRACLEAN 5W-30 is intended for compatible gasoline engines requiring SAE 5W-30.
- Passenger cars
- SUVs
- Crossovers
- Light-duty trucks
- Gasoline direct-injection engines
- Turbocharged gasoline engines
- Vehicles originally specifying applicable earlier API or ILSAC categories
The correct viscosity and specification should always be confirmed in the vehicle owner's manual.
Current vs. Older GTX ULTRACLEAN 5W-30
Older Castrol documentation listed:
- API SN PLUS / SN
- ILSAC GF-5
- Ford WSS-M2C946-A / WSS-M2C946-B1
- 45% cleaner than the API SN PLUS sludge-test limit
The current 2026 formulation lists:
- API SQ
- ILSAC GF-7
- Ford WSS-M2C946-B1
- Ford WSS-M2C961-A1
- Meets engine-test performance of Chrysler MS-6395
- 1.4X cleaner than the API SQ Sequence VH industry standard
The current specifications should be used when describing product being sold today.
Typical Technical Properties
| Property |
Typical Value |
| SAE Viscosity Grade |
5W-30 |
| Density at 15°C |
0.857 g/ml |
| Kinematic Viscosity at 40°C |
61 mm²/s |
| Kinematic Viscosity at 100°C |
10.2 mm²/s |
| Viscosity Index |
148 |
| CCS Viscosity at -30°C |
5,845 cP |
| Pour Point |
-38°C |
| Flash Point, PMCC |
200°C |
| Sulfated Ash |
0.78% wt |
Typical characteristics represent normal production values and should not be treated as guaranteed batch specifications.
Frequently Asked Questions
What is Castrol GTX ULTRACLEAN 5W-30?
Castrol GTX ULTRACLEAN 5W-30 is a synthetic blend motor oil designed for gasoline engines requiring SAE 5W-30. It focuses on sludge control, deposit protection, anti-wear performance and resistance to viscosity and thermal breakdown.
Is Castrol GTX ULTRACLEAN 5W-30 synthetic?
It is marketed as a synthetic blend motor oil, not a full synthetic.
Is Castrol GTX ULTRACLEAN 5W-30 API SQ?
Yes. The current February 2026 Product Data Sheet lists API SQ.
Does Castrol GTX ULTRACLEAN 5W-30 meet ILSAC GF-7?
Yes. The current formulation lists ILSAC GF-7.
Did Castrol GTX ULTRACLEAN 5W-30 used to be API SN PLUS?
Yes. Older product documentation listed API SN PLUS / SN and ILSAC GF-5. The current formulation has been updated to API SQ and ILSAC GF-7.
Is API SQ backward compatible with API SP and API SN?
API SQ is backward compatible with applicable earlier gasoline-engine API categories. The engine must still require SAE 5W-30 and must not require a separate specification that the oil does not meet.
Does Castrol GTX ULTRACLEAN clean sludge?
The formulation is designed to help clean existing sludge and help prevent new sludge formation.
What does 1.4X cleaner mean?
Castrol states that the current GTX ULTRACLEAN 5W-30 formulation is 1.4X cleaner than the industry standard as measured in the API SQ Sequence VH sludge test.
Is the older 45% cleaner claim still current?
The current 2026 Product Data Sheet uses the newer 1.4X cleaner claim measured against API SQ Sequence VH limits. The 45% claim was associated with older API SN PLUS documentation.
What causes engine sludge?
Heat, contaminants, frequent short trips and extended oil-change intervals can all contribute to sludge formation.
What does Castrol's 3X Protect formula mean?
The current Castrol GTX positioning focuses on fighting three common causes of sludge: heat, contaminants and short trips.
Does Castrol GTX ULTRACLEAN 5W-30 meet Ford WSS-M2C946-B1?
Yes. It is listed as meeting Ford WSS-M2C946-B1.
Does Castrol GTX ULTRACLEAN 5W-30 meet Ford WSS-M2C961-A1?
Yes. The current Castrol information lists Ford WSS-M2C961-A1.
Does Castrol GTX ULTRACLEAN 5W-30 meet Chrysler MS-6395?
The current Product Data Sheet states that it meets engine-test performance of Chrysler MS-6395.
Can GTX ULTRACLEAN 5W-30 be used in turbocharged engines?
It can be used in compatible turbocharged gasoline engines when the manufacturer specifies SAE 5W-30 and a performance standard met by this product.
Can Castrol GTX ULTRACLEAN 5W-30 be used in GDI engines?
Yes, where the gasoline direct-injection engine specifies SAE 5W-30 and a compatible API, ILSAC or manufacturer specification.
What is the viscosity of Castrol GTX ULTRACLEAN 5W-30?
Typical kinematic viscosity is 61 mm²/s at 40°C and 10.2 mm²/s at 100°C.
What is the viscosity index?
The current Product Data Sheet lists a viscosity index of 148.
What is the pour point?
The typical pour point is -38°C.
What is the flash point?
The current Product Data Sheet lists a typical PMCC flash point of 200°C.
Is Castrol GTX ULTRACLEAN the same as Castrol GTX Full Synthetic?
No. GTX ULTRACLEAN 5W-30 is a synthetic blend formulation, while Castrol GTX Full Synthetic 5W-30 is a separate full synthetic product with its own performance claims and approvals.
Is Castrol GTX ULTRACLEAN a high-mileage oil?
No. It is not the same product as Castrol GTX High Mileage. Drivers specifically looking for a high-mileage formulation should compare the applicable GTX High Mileage product.
Can I use Castrol GTX ULTRACLEAN 5W-30 instead of 5W-20?
Only if the vehicle manufacturer permits SAE 5W-30. Do not change viscosity grades without checking the owner's manual.
How often should Castrol GTX ULTRACLEAN 5W-30 be changed?
Follow the vehicle manufacturer's recommended oil-change interval or oil-life monitoring system. The product type does not override the prescribed maintenance schedule.
