I've been using DOT 5 for more than 30 years in all my 240Z's. The last brake master cylinder in the Blue 72 {I'm the original owner}, lasted more than 20 years. The car still has the original rear wheel cylinders. DOT 5 preserves the rubber seals - and it doesn't absorb moisture - so it all but prevents the usual corrosion you seen in the wheel cylinders and master cylinders. DOT can be hard to bleed - but not so much if you don't get air bubbles in it to begin with - Don't pour DOT 5 out of the can and into an existing pool of DOT 5, or an empty reservoir. That is how you get air bubbles to begin with. - I use a "V" shaped piece of metal a little longer than a butter knife - and I poor the fluid out of the can directly onto that - and let it run into the Brake/Clutch master cylinder reservoirs. Sound like the guy that owned the car - knew what he was doing. The only time you don't want to use DOT 5 - is for competition/racing. If you overheat DOT 5 - it becomes compressible and you get sudden brake fade.. If you are not melting the wheel bearing grease - you won't have any problems with the DOT 5, once you get the system bleed. FWIW, Carl B.