I have a 1970 Case 580ck that does not get used very much. I replaced a leaking hose on the front end loader but now I am leaking around a seal on one of the front loader arms. Is it because of lack of use? Is there an additive I can put in the hydraulic fluid that might swell up the seals? Thank you in advance for your time and expertise on this.
The seals rot and no additive will fix that.
No. It's been 54 years on the OEM seals or maybe 25 on replacements, might be time for some TLC.
Snake oil!! After it is in the system, you will still need to replace the seals, and who knows what else from the damage of the snake oil.
Just bite the bullet and reseal the cylinder. If it leaks oil out, it can also let in dirt or water which usually causes it to leak worse
Time for a reseal. No real way around it unfortunately.