Back in the dark ages, a lot of the little 6-ounce cans of Casite Tune-Up were used to clean and lube wiper motors. I haven't seen Casite in about 20 years but any lightweight tune-up oil should do. (Rislone, Wynn's, etc.) There is an inlet port hose nipple on the wiper motor that supplies the air to the vacuum motor. Attach a short piece of vacuum hose to the nipple and submerge it into the container of tune-up oil and run the wiper motor until the container is empty. It will be drawn into the intake manifold and clean the wiper speed control along the way. Then it gets pulled into the engine and cleans the valve guides!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!