When I bought my 1986 Plus 4 from the factory the first thing I did was to flush out the DOT 4 and replace it with DOT 5 silicone at first service. Since I used the car only for a month every two years as I was living overseas and car was in storage in between. In 2012 I shipped it to the U.S. and put it on the lift and drained the silicone. Looked good as new. I just flushed it again last weekend and still good as when I put it in. I have had my 1958 +4 on silicone since around 1976 since I was living in a very high humidity area of the world. I flush and replace every 10 years whether it needs it or not. Have not put silicone in the M3W(2012) yet. Living in Arizona we pray for rain and humidity!
