Try this:
Here's how to lubricate the motor, which should be done three or four times a year:
1. Remove the vacuum hose at the wiper motor. Lightly hold your finger over the hose nipple on the motor and cycle the wiper blade back and forth.. Note that in one direction the motor sucks in air, and in the opposite direction, the motor expels air through the nipple. Place the wiper blade in the position such that the motor will begin to suck air at the nipple.
2. Attach a six‐inch long piece of hose to the motor nipple and hold the open end up. Using a squeeze bottle, force one teaspoonful of lubricant into the hose.
3. Cycle the wiper blade back and forth several times. Repeat the process again, adding a second teaspoonful of lubricant.
4. Start the engine and run the wiper motor. It should run well. If it does not, the wiper motor should be disassembled, cleaned, inspected and a rebuilding kit installed. It is normal for the wipers to slow down when the car is accelerated, but they should not stop altogether.
Use a light machine oil such as 3 in 1.