Looking at the parts image and your description , it seems that the springs are integral to holding the fork leg ( lower portion that holds the axle ) from slipping off the fork tube .
I'm thinking , if the springs are that weak , stretching them may not hold for very long . Still , it might be worth a shot . I've done so in different applications , with good results .
Replacing with a stiffer spring might help .
But , for simplicity sake , the compression springs you bought at the hardware will likely do as much or more good .
If there really is no valve in the forks , then the oil would only be good to keep things lubed and not corroding .