How Extreme Heat Affects Your Engine

A modern passenger car/light truck engine can surpass 230°F (110°C), and higher if towing or hauling heavy loads at the...

May 21, 2021

A modern passenger car/light truck engine can surpass 230°F (110°C), and higher if towing or hauling heavy loads at the height of summer. Many vehicles today use smaller, more power-dense engines to allow automakers to meet tighter fuel-economy regulations without sacrificing power.

Turbochargers are key to striking the optimum balance between fuel economy and power/torque, which is why you can find them on many new vehicles. While they enhance performance, turbos come with a downside: they create extreme heat, which can reduce engine performance and life if your oil isn’t up to the challenge.

Heat can create deposits & sludge

Heat can quickly break down motor oil, creating deposits on the intake valves, which impede airflow into the engine and contribute to poor sealing of the combustion chamber. This can lead to…

  • Rough idle
  • Misfire
  • Reduced power
  • Reduced fuel economy

Extreme heat also depletes the oil’s additives sooner, altering the oil’s chemistry and preventing it from lubricating, cooling and protecting as designed. Sludge can form, which clogs narrow oil passages and prevents oil from reaching vital components, causing wear. Preventing sludge is particularly important in engines that use variable valve timing (VVT). Intricate parts sensitive to sludge can fail to operate properly, resulting in reduced performance.

AMSOIL Signature Series Synthetic Motor Oil has 50% more detergentsD to help keep oil passages

clean and promote oil circulation. Engine failures due to sludge are often caused by a plugged oil pick-up tube screen – the motor is effectively starved of oil.

The Sequence VG Engine Test measures an oil’s ability to prevent sludge. During the test, a Ford* 4.6L engine is subjected to sludge-inducing conditions for 216 hours. The industry standard allows for 10 percent blockage before the motor oil fails the test.

Signature Series produced a screen virtually free from sludge (see image). Its detergent and dispersant additives are so effective, Signature Series provides 90% better protection against sludge.DD


Signature Series virtually prevented sludge on this oil pick-up tube screen.

Deposits reduce turbocharger performance

Turbochargers rotate up to 300,000 rpm, which is 50 times faster than an engine running at 6,000 rpm. In addition, the exhaust gases that spin the turbine can exceed 1,000°F (538°C). Extreme speed combined with intense heat can create deposits on the turbo shaft and bearing, known as “turbo coking,” which can reduce performance and ultimately ruin the turbo.

Motor oil is responsible for cooling and lubricating the turbo, meaning it’s best to use the highest-quality oil you can find to protect your hot-running, turbocharged engine.

AMSOIL Signature Series fits the bill. It’s formulated with premium synthetic base oils that naturally resist heat and top-shelf additives to help keep components clean. In fact, it protects turbos 72% better than required by the GM dexos1 Gen 2 specification.C


Signature Series controlled heat and minimized performance-robbing deposits on the turbo-bearing and shaft surfaces.

In extreme heat generated by today’s turbocharged engines, Signature Series’ high-performance additives and quality base oils offer improved resistance to heat, maximizing the performance and life of your engine.

Dvs. AMSOIL OE Motor Oil, DDBased on independent testing of AMSOIL Signature Series 5W-30 in the ASTM D6593 engine test for oil screen plugging as required by the API SN specification. CBased on independent testing of AMSOIL Signature Series 5W-30 in the GM turbo coking test. *All trademarked names and images are the property of their respective owners and may be registered marks in some countries. No affiliation or endorsement claim, express or implied, is made by their use.