Hello, have from the estate of someone a brake fluid stester. If I hold it in my brake fluid tank and in my girlfriend it shows 1 %.. If I hold it under the faucet full 4%. The results are good, but can I check somehow if it actually works properly? Or is the technology so simple that there is no possibility of distortion? PS: I think on both vehicles the brake fluid has been no more than 2 years Is it really safe that the brake fluid water mixture is not in the pipes? Greetings & Thank you