With 8,24 GtCO2 emitted in 2019 (pre-COVID), the transport sector is responsible for around 25% of total CO2 emissions worldwide [1] and more than 31% in France (2021) [2]. Moreover, this sector contributes to NOx and particles emissions which are harmful both for the environment and human health [2]. In this context, research on electrification and alternative fuels rallies scientists and industries. While batteries and electrical engines seem a promising solution for individual vehicles, thermal engines with carbon-free fuels seem to be better suited for certain applications, such as trucks, trains, or ships [3]. As a versatile energy carrier and carbon free fuel, hydrogen is considered one key element for decarbonization, but it faces important challenges, such as storage and transportation [3]. Ammonia, another form of the hydrogen, is more and more considered as an efficient hydrogen carrier [4]. Hydrogen and ammonia can be directly used as fuel but with several differences compared to conventional hydrocarbon fuels [4]. To be efficient, existing thermal engines must be adapted to these new fuels. While an increasing number of studies focus on the optimisation of engine design [5–7], some compatibilities must be assessed for these molecules with a particular reactivity, as with the lubricant. In thermal engines, lubrication is a key challenge to ensure moderate fuel consumption, high energetic yield, and engine durability. The lifetime of lubricants is usually determined by their consumption rate, and resistance to oxidation. Oxidation engenders impurities, degradation of the lubricants’ integrity and modification of their friction reducing ability [8]. These new alternative fuels impose new constraints, the effect of which regarding lubricants’ integrity and properties must be studied to guarantee proper functioning and reasonable drain intervals. The effect of ammonia, hydrogen and their blends on lubricants in thermal engines is a relatively new topic in the literature [9–11]. Yet, lubricants degradation processes have been studied in other contexts, with hydrocarbon fuels [8,12], or in compressors using ammonia as a refrigerant for example [10]. This work presents a synthesis of phenomena observed in the literature which could take part in the ageing of lubricants in ammonia and/or hydrogen engines, with a special focus on ammonia. The methodology chosen to perform lubricant study is described here.