Hello all,

I got a problem which I think is being caused by a failing
master cylinder but wanted to make sure before I go out and buy one. I
am noticing that every 5th time that I brake, the brake pedal will go
down to the floor more significantly than normal. What is odd is that
this is only occurring when the rotors warm up. In the morning I do
not notice this, but could also be because of highway driving. Do I
have a master cylinder which is beginning to fail? Also I see that the
OEM master cylinder costs about $250 and one from Autozone costs $50.
Besides that the one from Autozone is a rebuilt one, is there any
other reason why I should go with OEM?

Thanks in advance for all of your help,
Nick