[GreenKeys] Model 20's and Oil

[Jim Haynes]

On Wed, 21 Jan 2009, George B. Hutchison wrote:

> The solution to high temperatures is a 50/50 by volume mixture of 30
> wt non-detergent oil and Andy Granatelli's STP oil additive. The oil
> will carry the STP into the mechanism and the STP will stay behind
> and lubricate while the oil turns to vapor and drifts away in the
> evening breeze.
>
This happens to be the mixture that Digital Equipment Corp. told their
field service techs to use.  This was specifically on Model 33 machines
used with their minicomputers, where the supposedly light-duty
machine was in fact run 24/7.  I have no idea what Teletype thought
of it - Teletype continued to recommend nothing but KS-7470 oil
to the end (except that some of the late products had some special
lube requirements).

Both KS-7470 and Three-in-one oils have very distinctive odors (but
not the same for both).  I don't know much chemistry, but the odor
indicates the presence of some volatile compound.  Maybe the purpose
of the volatile is to thin the oil so it gets into the small clearances
and then evaporate leaving the oil behind.  Someone recently wrote that
Teletype oil stinks.  I of course had to correct him; it's the
sweetest of perfumes to the green key afficionados.

Jim W6JVE