Thats because your MGA leaks ALL fluids like all early British cars marking their spots. Seriously, just do a search on DOT 5 vs DOT 3. There are good things about DOT 5, however it doesnt like most of the seals out there and it will cause them to swell and loose durometer. You just have to get the correct seal material for DOT 5.

here are the search results http://www.google.com/custom?domains=www.stovebolt.com&q=DOT+5+brake+fluid&sitesearch=www.stovebolt.com&sa=Search&client=pub-3699152422294193&forid=1&ie=ISO-8859-1&oe=ISO-8859-1&cof=GALT%3A%23008000%3BGL%3A1%3BDIV%3A%23336699%3BVLC%3A663399%3BAH%3Acenter%3BBGC%3AFFFFFF%3BLBGC%3A336699%3BALC%3A0000FF%3BLC%3A0000FF%3BT%3A000000%3BGFNT%3A0000FF%3BGIMP%3A0000FF%3BFORID%3A1%3B&hl=en

The problems we face today can not be addressed at the same level of intelligence we were at when we created them - Albert Einstein Or with the same level of $ - Me