I have tested various oil samples from parts requested by the client to the
contract standard. The current standard requested is ISO 4406 _12/10. The
recomended oils in some cases are specified _/15/12 and that this would be
out of the contractual requirement. The other oils are specified by the manufacturers under ISO VG 150 and ISO VG 46. With the first sample
specified as _/15/12 and a viscosity of ISO VG 32, can I relate the viscosity value to the purity and would this mean that the recomended oils would be lower grades than required by the contract.