Much of my discussion around which oil is best suited for our 1.4L Turbo comes with turbo longevity in mind. With turbocharged engines, such as the ones you find in the Cruze 1.4L Turbo, these become very important metrics to consider when choosing an engine oil. I've always advocated for AMSOIL Signature Series' group 5 ester base oil being vastly superior to anything else on the market on the basis that it significantly reduces deposit formation around piston rings and turbo seals (which are actually quite similar), as well as turbo bearings. This characteristic is directly correlated to oil consumption caused by "worn" turbo seals as well as clogging of feed lines and premature turbo bearing failure.
Since I prefer to remain technical, however, I'd like to explain this in a scientific manner. The API SN Resource Conserving specification requires a number of tests be performed in order to meet the specification, among which is ASTM D6335 bench testing, also known as TEOST 33C. This is an industry standardized testing method for determining the rate of high temperature deposits due to thermo-oxidation in engine oils. It is a simulation test that, in layman's terms, measures the amount of deposits, in grams, left behind by engine oils and is designed to simulate turbocharger operating conditions. These are all tested by an independent third party to guarantee accuracy.
So, how do your favorite oils fare? So far, I've come across three in AMSOIL's latest publication; for AMSOIL Signature Series, Royal Purple API, and Mobil 1 EP.
AMSOIL deposits: 7 mg
Royal Purple deposits: 25.4 mg
Mobil 1 EP deposits: 28.2 mg
API SN Maximum: 30 mg
As a result, AMSOIL Signature Series 5W-30 protects against harmful deposits on turbochargers over 4x better than Mobil 1 and 3.6x better than Royal Purple. With turbo replacements coming in at over $1,000, a few extra dollars an oil change is cheap insurance to ensure you have the best protection possible under those conditions. Feel free to dig up the TEOST 33C results for your favorite oil (it's a required test to pass API SN certification), but in my research and experience, AMSOIL's ester based oil provides among best, if not THE best deposit prevention performance of the dexos1 compliant oils available for our cars.
AMSOIL Signature Series 5W-30 Synthetic Motor Oil
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