So I drove the car through the snowstorm but only for 20 miles this past Saturday. As usual, under snowy conditions, the ESC and ABS were used a lot. Does that waste brake fluid or overusing them or braking really hard use brake fluid or contribute to a brake fluid leak? Anyways, on Sunday (yesterday) the brake fluid warning would go on and now it's continusously where where it says brake fluid low and the parking brake light is also on along with it. I checked the reservoir adn there was still brake fluid there, though it might not have been completely full. Could this be a sensor issue or an issue caused by overusing the abs or esc, and can braking too hard in snowy conditions warp the braking system or the sensor? I will try to top it off with a small bottle of valvoline I'll buy on the way home this afternoon. I have the large bottles of brake fluid, but I heard once you break the seal, you can't use it because it gets exposed to oxygen, so rather than wasting all that fluid, I'll just buy a small bottle of valvoline dot 3/4 and top it off and see if the warning light goes away. But could this be due to an actual leak or somethign that has to do with braking too hard in the snow? It was completely fine one day and the next, it went off. And is the parking brake actually engaged when that parking brake light lights up on the dashboard, or is it just using the same light to attract attention to an issue in the braking system? The nearest oreilly's is only 4 miles away, so I should be safe for now before topping it off to see if it goes away. I also had a question about the brake fluid. They say after you break the seal you can't use it, but for how long? I'm assuming if I break the seal, and if I have a leak and I need to top it off every day, then the next day, my fluid should still be fine, but maybe after sitting for a month, it won't be fine, so when is that threshhold reached? 1 week after braking the seal? Right away? 1 day, 1 month? I know 1 year definitely will be too long but if I do have a leak, I could keep my brake fluid that I buy today and use it for topping off temporarily, but by what time will it completely go bad and shoulnd't be used for topping off either? Thanks.