well i have a uni filter that required oiling like once every 2 weeks, so that the suction of it will run smoothly
oily 1's are very high maintenance and must be looked after
some says the dry 1's are much better than the oily 1's well i say SAME SAME BUT DIFFERENT
its really up to you really thought, it just that if you have the oily 1 and dont look after it , you can easily wreck it and have to buy a new foam replacement
how do you find the uni filter ???
have you tried other filters ?? and comparison ??