I'm not saying use it but I'm pretty sure it could work just fine. Any light lube that wont attack the seals should potentially do the job. I used some Finish Line wet weather chain lube a year and a half ago and the brake still works fine and hasn't sticked since. But it shouldn't be so hard to find some Shimano brake fluid, a lot of those brakes are sold and some people and bike shop do bleed them.