This wasn't any sort of 'seal leak'...just plain O'Riley's AW-32 hydraulic oil.
I agree that it's a false economy to cheap-out on the oil in a properly functioning suspension system. But, in Thing One's case, it was leaking like a sieve when we got the car and he needed to be able to get to NY without running the system dry. We didn't have the time, money or inclination to replace the struts so I opted for the O'Riley's solution. For some realon, the leaking stopped and it has worked fine ever since (10,000+ miles).