||seen pretty weird failures on low mileage, otherwise super clean cars when non DOT3/4 fluids got used.
I have a series of cars over the past few years that all hard Dot 5.1 fluid in their systems per the owners. ABS leaks, master cylinder leaks, and weird plastics and seal failures all followed. While the fluids might be compatible, I'm not sure that all the legacy seals, orings and plastics are.
1992 TT w. 80K
1992 TT w. 60K
Bernie Bilski firstname.lastname@example.org
President of Z-Car Club of Northern Virginia
1995 Nissan 300ZX TwinTurbo in Cobalt Green
1997 Nissan 240SX SE in Ultra Red
2006 Nissan Frontier SE in Ultra Black