If you are sure it is oil then it has to be coming out of the gearbox. Machine will have to be dismantled & gearbox removed to replace the oil seals & refill the gearbox with fresh oil. It may be just black marks coming from a build up of old soap & softener. Best way to get rid of that properly is to get the inner drum removed & all build up scrubbed away. Anything else doesn't really get rid of all of it.
Lincoln Appliance NZ
February 2011
not familiar with simpson but if its a top loader oil leakage suggests seal failure allowing water down which forces oil up the shaft into the drum, if its a front loader you have bearing failure but this would be grease smears rather than oil
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