The turbocharger/direct fuel injection combo has emerged as automakers’ favored choice for producing powerful engines and meeting government fuel-economy requirements. The increased airflow turbos generate enables an engine to burn more fuel and produce more power, but this power comes at a cost. The tremendous heat and stress turbos create cause some oils to break down and form harmful bearing deposits through a process known as turbo coking. Over time, turbos can suffer reduced performance or fail altogether.
How Turbos Could Slow You Down
The deposits common to turbochargers can lead to:
- Blocked oil passages, oil starvation and eventual failure
- Reduced turbine speed – resulting in lower boost pressures, reduced performance and poor efficiency
- Oil breakdown and oil burning
- Expensive turbo rebuild or replacement
The GM Turbo Coking Test
The Turbo Coking Test was designed to simulate the extreme operating conditions of a turbocharged engine. It evaluates a motor oil’s ability to resist deposit buildup in the oil passages and bushings of a turbocharger. Temperature increases within the turbo and the weight of any deposits are recorded.
Test Parameters
| Engine | 2012 GM 1.4L |
| Duration | 2,000 cycles of extreme heat soaks – approximately 537 hours |
| Measures | A motor oil’s ability to resist deposits in a turbocharger’s oil passages and bushings |
| Simulates | High-heat operation of a turbocharged engine |
| Requirement | Temperature change within the turbocharger limited to 13% |
Signature Series protects turbochargers 72% better than required by GM dexos1® Gen 21
The GM Turbo Coking Test requires an oil to limit the temperature change within the turbocharger to 13% or less to pass the test. Signature Series limited the temperature increase to only 3.6%, controlling heat and proving it protects against deposits common to high-temperature engine environments.
1Based on independent testing of AMSOIL Signature Series 5W-30 in the GM Turbo Coking Test as required for the GM dexos1 Gen 2 specification.
All products advertised here are developed by AMSOIL for use in the applications shown.