LeakyBoot,
Finally got to the shop today and got the Cat part number for the wiper lubricant. Cat Part Number is 8X1153, bad news is when I checked in SIS it comes back "Check dealer for availability" which probably means obsolete but migh be some on the shelf covered in dust!
The bottle says it was made by/for Sprague wiper company. Also mentioned it was silicone base liquid, looks to be about SAE 10 weight oil or lighter.
Did a bit of search online for them and could not find a source for the lubricant, but did find this information:
PREVENTATIVE MAINTENANCE − Additional Lubricants Added To the Motor
Additional lubricants can be used as a preventative maintenance or as a field fix for sticky units. If "O"rings are not damaged and the motor is not frozen, lubricant injected into the air lines will keep a motor running. We recommend that one half ounce be injected into each motor at a location as close to the motor valve as possible. Allow motor to run fifteen minutes (remove arm or place a rag under blade) to work the lubricant through the valve. On an average system, lubricating in this manner every six months is sufficient. Where heavy contamination is present, more frequent applications may be required. This is not a substitute for proper maintenance but can give relief for most contaminated systems. A light viscosity, wax−free oil is recommended. Do not use any type of penetrating fluid or oil. While these will free a motor, they may do more harm than good. They will break down lubricants in the motor and attack "O"rings. Most are not intended for pneumatic use. Only under emergency situations should these be used and shoud be followed by the addition of lubricating oil and possibly a breakdown and manual regreasing of the motor.
I'm thinking something like good old 3 in 1 Oil would work just fine.