I've got a 15 year old truck that isn't too badly rusted for its age, and I want to keep it that way. The rear axle is red, some of the brake and fuel lines are not leaking but show blooms of corrosion, and towards the front one part of the frame has some perforations. It's under the accumulator and a/c evaporator both.
As I want to keep this for at least another 5 years, I'm wondering if undercoating makes sense?
The local toyota dealer wants $100 to undercoat the frame, $150 if I do floorpans too. Err, that's an inside deal. Retail might be higher.
They say there's an official toyota product that's a rust inhibitor, also, and claim that it's not an issue if there's already rust present (that it won't trap and seal in moisture, just exacerbating the issue), and that they spray something else inside the frame rails also.
I understand that a modern unibody car rarely benefits from undercoating, but this is an older full-frame truck, and it's rusting.
Does undercoating make sense?
or can it trap in rust and salt?
Alternatively I've heard that just spraying oil can help?