Re: [TUHS] the distinct smell of light machine oil, was Re: TUHS Digest, Vol 33, Issue 7

On 09/08/2018 15:15, Derek Fawcus wrote: Ordinary WD40 is NOT silicone based (obNitPick: note the 'e': not silicon, which is a hard crystalline substance). There is a "specialist" silicone-based version but ordinary WD40 is hydrocarbon based, being a mixture of light paraffin (naptha to transpondians, ie the stuff that's used as a solvent or fuel) and a paraffin wax, as stated in the manufacturer's official MSDS document. The characteristic smell is largely from an aromatic hydrocarbon additive. And not much else, because like a lot of simple hydrocarbon oils developed half a century or more ago, it oxidises to a gummy substance. The Teletype manual definitely doesn't suggest 3-in-One oil and some sources suggest it's too thick anyway. The manual in front of me specifies two Western Electric part numbers for oil and grease. It's been discussed more than once on the Greenkeys list, and there's a useful page listing modern equivalents at Doug Jones' page: https://homepage.cs.uiowa.edu/~jones/pdp8/UI-8/ks7470oil.shtml -- Pete Pete Turnbull