Why can’t I use synthetic oil in my wood chipper?

We’ve been asked time and time again; why can’t I use synthetic oil in my wood chipper? Oils are rated on their viscosity, which measures their ability to flow over a period of time at a nominal temperature. Both synthetic and conventional motor oils are tested the same way for measuring their viscosities. Synthetic oils are artificially created to be more consistent than conventional. This is especially true when you look at the molecular level of a single drop of oil. You will find millions of tiny similarly sized and shaped particles. This is what makes synthetic oils flow so easily and feel more slippery than conventional oil. While this is great for your car or trucks engine, it does not perform well in a hydraulic setting. Conventional oils are not consistent at their molecular level, exhibiting a wide variation of size and shape particles; thus less consistent than synthetic. It is this inconsistency at the molecular level that makes conventional oil a better suited performer in a hydraulic application where pressure (or resistance to flow) is required. These little inconsistencies in shape and size are what helps build and maintain pressure whereas synthetic oils will flow but not build pressure like their conventional counterparts. Ex: Synthetic Oil is like funneling sand into a jar, while conventional oil is like funneling pebbles into a jar. A diagram below helps illustrate this: