EP (extreme pressure) oils were developed in the thirties for Hypoid rear axles where sliding friction was great.
They will however attack phosphor bronze bearings so are a no-no for Scott gearboxes UNLESS of a “modern” formulation which will not affect phoshor bronze – so you need to check with the individual oil supplier.
Having said that, a straight 40 or 50 grade oil – such as provided off the shelf by Morris Oils is quite adequate for a Scott Gearbox.
Resist the temptation to use “thick” oils given the design does not employ any seals as such – as thick oil will both cavitate and not adequately flow into the bearings. Better to suffer some oil loss than starve the internals.
Stan Thomas.
