Portable compressors can now be described as "oilless" or "oil-free". This means that the interior components are coated with friction-reducing coatings, instead of traditional oil lubrication. The main benefit is that you won't need to change your oil. All of our compressors were tested for garage usage. However, the oil content varied between the larger models. If all other specifications are identical, then we would consider the oil-free model to be an advantage.