There is a sticker in the engine compartment of my MK2 warning that the brake system has been converted to DOT5 silicone brake fluid. When I went to top off the fluid, I noticed that it was an dirty amber color rather than the purple I'm used to seeing. A few drops in a jar of water easily mixed and confirmed that the system is filled with glycol-based brake fluid.

Who the heck changes a system back from DOT5 and doesn't bother to remove the warning sticker?

For the record, I'm a fan of DOT5. Had it in my TR4 for 10 years or so with no issues.

 

Maybe someone added some glycol stuff somewhere along the way and didn't care.


If you were to open up one of the rear bleeders and let a few drops out to test.


I have some Dot 5 on the shelf and the purple dye oxidized to an amber colour _ not that this has anything to do with what we're discussing here, but I didn't expect it to do that.

 

I had to change the brake light switch this weekend and tested a few drops of the fluid that came out when I removed the switch - its glycol-based. I'll do a full system flush and refill later this week with fresh DOT4, remove the sticker, and leave it at that.

 

Be aware. As I was doing brakes on a newer Land Rover I needed synthetic Castrol DOT4. Ordering some in for the job the containers were black. Went and got the white LMA Castrol DOT4 and it too is synthetic. So all this time I thought Castrol DOT4 was regular type fluid until I finally read and compared labels. Have used Castrol for 40 yrs.

 

My understanding is synthetic and silicone are not the same. Someplace I heard that DOT 3 and 4 are technically synthetic.