Any oil has risk, even those sold at vap shops for "pleasure". From the American Lung Association:
Essential Oil Health Claims- Fact or Fiction?
Be cautious about broad health claims about essential oils. Scientific research on the efficacy and safety of essential oils for specific health conditions is limited and more evidence is needed. Some research even shows adverse health outcomes from essential oil use. For example, a 2022 study of 200 individuals demonstrated the negative association between the use of essential oils and cardiopulmonary health. Study participants who inhaled essential oils one hour or more each day had increased heart rate and blood pressure and a decreased lung function rate.
Aromatherapy is one of the oldest and most common uses of essential oils. Much of the research published on the benefits of aromatherapy focuses on the use of a single essential oil. However, in aromatherapy, essential oils are frequently used together. There is limited research on the combinations of essential oils, interactions between the chemicals, impacts on medications and impacts on health. It is well known that when some VOCs are combined, secondary pollutants such as formaldehyde (a known nose, throat, and lung irritant) may be produced.
Though some essential oils, such as tea tree oil, have antimicrobial properties, the benefits are minimal. Research suggests that the antimicrobial effect of essential oils could only be found during the first 30-60 min after the evaporation began. This was especially in the case of tea tree oil and means that continued use or diffusion for the purpose of disinfection is ineffective.
And for the comment to prevent red rot, research as quoted above disproves that theory. I have in the past diagnosed 2 patients, one 18 years old and another 21 years old with pulmonary hypertension and right sided heart failure attributed to vaping.
So I side with Rowuk. No benefit and possible risk. Please do not run valve oil down the lead pipe.