Q: I have white powder substance on metal parts of my engine on my 13 Toyota Sienna, 54,000 miles. Should I worry about corrosion?

If the material (the white powder substance) is observed on aluminum parts, that just surface corrosion of the aluminum. The surface aluminum has oxidized and produced aluminum oxide (a white powder). This kind of superficial corrosion is meaningless insofar as any possible negative effects on the car. In terms of corrosion on a car, a principal concern is fuel and brake lines mounted to the underbody. Usually, components under the hood are well protected and any moisture that is there evaporates due to the heat (moisture greatly accelerates corrosion). If corrosion is a concern, the real issues are typically beneath the car and, again, fuel and brake lines are the principal concern. Typically, after 15-20 years, unless the car has been operated only in the desert, all of those lines beneath the car will have to be replaced. If you have further questions or concerns, please do not hesitate to re-contact YourMechanic as we are always here to help you.