Is it OK to use synthetic brake fluid instead of conventional brake fluid for the ST?

Joined
Aug 30, 2008
Messages
98
Location
Jenks, OK
Bike
2017 BMW R1200GSA
I stopped by an AutoZone to pick up some brake fluid for the ST and pretty much all the DOT4 brands were synthetic. Maybe it's something I hadn't noticed before. Is it OK to use synthetic brake fluid? I don't really care for the Honda brake fluid but is it synthetic or conventional? I bought some Honda brake fluid at a dealership once and the foil seal had come undone and the fluid had a weird color to it so I tossed it.
 
Re: Is it OK to use synthetic brake fluid instead of conventional brake fluid for the

I have been using a Valvoline Synthetic Dot 4 for years in all my bikes. I like it a lot better than the no synthetic stuff.
 
Re: Is it OK to use synthetic brake fluid instead of conventional brake fluid for the

I'm a little confused about brake fluids. I've used Castrol LMA brake fluid in the past. They claim it exceeds DOT 3 & DOT 4 requirements, but doesn't state that it's DOT 5 (silicone).
I know that silicone brake fluid is verboten in ST's, so what's the real story on the Castrol LMA stuff? Is it silicone or synthetic or what?
 
Re: Is it OK to use synthetic brake fluid instead of conventional brake fluid for the

As long as it meets the Dot 4 you will have no problems with the fluid.
 
Re: Is it OK to use synthetic brake fluid instead of conventional brake fluid for the

...what's the real story on the Castrol LMA stuff? Is it silicone or synthetic or what?

It's a synthetic, glycol-based DOT 4 fluid, which is fine for use in your ST. LMA is just their marketing term for "doesn't absorb as much water as the stuff those other guys make."

Anything that says DOT 3, DOT 4 or DOT 5.1 is glycol-based; DOT 5 is silicone. That sounds confusing (and it is), but the 3/4/5 series numbers are more-stringent standards that don't dictate composition. Early DOT 5 was silicone; 5.1 is still technically 5, but they issued another number to keep people from damaging their systems by mixing the two.

DOT 5.1 will work in systems designed for DOT 4 only if you're doing a full re-build and have completely clean parts. Otherwise, if you've got DOT 4, stick with that. It's not going away anytime soon.

--Mark
 
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