I filled my mountain bike brakes with baby oil for a year and here are the results!
Why Bicycles Stack Exchange recommends it
Bicycles Stack Exchange users link it as real-world evidence when asked about substituting other oils or lubricants for brand-name brake fluid.
Recommended by 0 people across 0 different months, 2020 to 2022.
What it is
Berm Peak's Seth Bike Hacks reports on a year-long experiment running baby oil instead of Shimano mineral oil in the rear hydraulic brake of a fat bike. He then tears the brake down and inspects the seals and other vulnerable parts under a microscope for degradation. It is presented as entertainment, not a recommendation.
What people said
Cites Feldmarshall · 2020-02 · Bicycles Stack Exchange · on “Alternatives for mineral brake fluid / oil (in a pinch)”
Seth from "Seth Bike Hacks" youtube channel did a test recently with a baby oil, including disassembling the caliper and checking the seals for damage under a microscope. Full video here [this video] . Also I remember reading in a review of Shimano brakes on bikeradar that in a post-crash pinch they used olive oil and got down the mountain OK. But this is rather an extreme example. The only substitute I have a personal experience with was using sewing machine lubrication oil in very old Magura brakes as a long-term replacement. It did not seem to damage the brakes, but for some reason required bleeding the breakes much more often. It is possible that it was slightly out gassing under temperature.
Cites Warren Burton · 2020-10 · Bicycles Stack Exchange · on “Using non-brand oil for cleaning brake pistons”
Probably you don’t need to be too concerned with different oil brands for the minimal quantity you’ll be using to clean the pistons. This guy put baby oil in Shimano brakes for a year and couldn’t tell the difference. [this video]
Cites jhnc · 2022-04 · Bicycles Stack Exchange · on “Can non-brake silicone lube be a good substitute for hydraulic seal lubricants in brakes?”
@mattnz Simple curiosity. If one can replace hydraulic fluid with baby oil [this video] , maybe one kind of silicone lube is just as good as another?