Low viscosity engine lubricants (LVO) are considered a possible solution for improving fuel economy in ICE. So, the aim of this study was to verify experimentally the performance of low viscosity lubricants regarding engine wear, since the use of LVO could imply unwanted wear performance. Potential higher wear could result in a reduction in life cycle for the ICE, a non-desired effect. In addition, currently limited data are available regarding “real-world” performance of LVO in a real service fleet. In this particular case, there were included out-of-specifications oils in terms of HTHS dynamic viscosity, where low viscosity was considered (3.0 cP), making this test highly interesting for industry. On this test 48 buses were monitored using a deep and extensive oil analysis program, comprising two engine technologies (Diesel and CNG), four engine types and three different lubricants, two of them LVO and other one as a reference baseline, during an oil life cycle of 30000 km, sampling 10 samples per bus. For every sample, a broad list of thermo-physical and chemical properties were measured, and specially wear engine was quantified using ICP-OES, in order to detect abnormal wear patterns in engines.