In Reply to: Re: Oil tested after 10 years use. posted by Tim Daley(MI) on December 10, 2018 at 12:43:35:
Total rubbish. We have been through this before and the nature of the chemical and molecular changes that engine oil undergoes inside an engine has been thoroughly and painstakingly studied and documented.
The base oil that is the foundational component of an engine oil is a carefully engineered mix of hydrocarbon molecules. The molecules in that mix can and do get aaltered when subject to heat and stress inside an engine. That means the carefully engineered physical makeup of the base oil is changed and the viscosity changes with them. In general engine oils initially start to shear down to a lower viscosity as the longer chain molecules are destroyed and the viscosity drops below the original SAE grade. Then over time oxidation causes polymerization of the molecules and the oil begins to thicken. If operated long enough it will become too viscous to measure. Simply put the base oil molecules first get shredded and then cooked into mush.
Used engine oil can be recycled but it takes a lot more than filters. It is reprocessed into a fresh new base oil via the same distillation / de-waxing / molecular cracking chemical processes that were used to refine the original crude oil. The amount of base lubricating oil that can be recovered from "good used" engine oil is about 60% by volume. The molecular fraction lost has been altered to the point it is no longer suitable for use as a lubricating oil.