Rehashing more information about the General Motors oil specification known as Dexos. We have some updated information concerning turbo charger protection. Our original article appeared in 2011 called “Dexos 1, AMSOIL’s Got it”
AMSOIL signature series is the highest formulated motor oil product available. Our full line includes OE (Original Equipment) and XL (Extended Life), which are great full synthetic oil products. The Signature series raise the bar even higher especially for modern day automobiles that include direct injection and turbocharging to maximize performance and efficiency.
Below is an article that was featured in the September 2018 AMSOIL Dealer Magazine. If you would like a copy of this article we would be glad to email it you.

AMSOIL Signature Series Oil Protects Turbochargers 72% better than required by GM Dexos1 Gen 2

The (GM) Turbo Coking Test subjects motor oil to approximately three weeks of extreme heat soaks in the intense environment of a turbocharged engine. AMSOIL Signature Series Motor Oil provided outstanding protection against the harmful deposits common to turbo charged engines.
The turbocharger/direct fuel injection combo has emerged as the 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.

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.

AMSOIL Signature Series Protects Turbochargers

The GM Turbo Coking Test requires an oil to limit the temperature change within the turbocharger to 13 percent or less to pass the test. Signature Series limited the temperature increase to only 3.6 percent, controlling heat and proving it protects against deposits common to high-temperature engine environments.
Signature Series controlled heat and minimized performance-robbing deposits on the turbo-bearing and shaft surfaces

(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 operations of a turbocharged engine
  • Requirement: Temperature change within the turbocharger limited to 13 percent

How Inferior Motor Oils Could Slow You Down

The deposits cause by lower quality motor oil (including other full synthetic and semi-synthetic brands) can lead to:

  • Blocked oil passages, oil starvation and eventual failure
  • Reduced turbine speed (the turbine is what speeds up airflow and is what make a turbo work) resulting in lower boost pressures, reduced performance and poor efficiency
  • Oil breakdown and oil burning cause other oil related problems in the engine (sludge, varish, viscosity increases and higher engine wear)
  • Expensive turbo rebuild or replacement


AMSOIL ASL 5w30 “Signature Series”

Engineered for enthusiasts seeking maximum protection and performance. Precision-formulated with cutting-edge technology and a longstanding devotion to making the world’s best motor oil. The result: engine protection that blows the doors off the highest industry standards.

  • 50% more cleaning power vs. AMSOIL OE Motor Oil
  • Ideal for turbos & direct injection
  • Guaranteed protection for up to 25,000 miles or 1 year (including severe service)
  • Protects Pistons from Low-Speed Pre-Ignition (LSPI)
  • Preserves Horsepower
  • Easier Cold-Starts
  • Maintains Protective Viscosity

You can purchase AMSOIL Signature Series Motor Oil for any turbo charged/direct injected engine. Use the correct viscosity according to your owners manual or use the AMSOIL Online Vehicle Lookup Guide.
Wholesale purchase options are available to those that qualify.

AMSOIL Buy Wholesale