Last year, amid the uproar of General Motors’ delaying safety fixes for millions of vehicles, we wrote about the gray area of vehicle safety, highlighted by a long-running probe into whether rusting brake lines in millions of older Chevrolet and GMC trucks were legally defective. Federal officials revealed their answer after four years of work: The GM trucks are not defective, but you should really wash your car.
The National Highway Traffic Safety Administration’s investigation of the GMT800 vehicles — Chevy Silverado and GMC Sierra pickups, and Chevy Tahoe/Suburban and GMC Yukon, among others built between model years 1997 and 2003— was the longest-running probe in the agency’s history. It found 2,702 complaints about rusted brake lines, including 88 crashes and 20 injuries. That probe only covered vehicles in “salt states” where winter requires frequent road treatments; for all 5.9 million GM trucks and SUVs nationwide, the totals were 3,049 complaints, 94 crashes and 26 injuries.
While GM has said the trucks should still stop even if a steel brake line rusts through and leaks, and that the vehicles would give some kind of indication about a problem, many owners who complained to NHTSA reported trouble stopping without warning.
Yet NHTSA found that the rates of complaints and failures were not significantly different from GM vehicles than they were in those from Ford and Chrysler, although the other two makers did have fewer complaints. It also found that most of the problems had begun after the vehicles were at least seven years old and residing in salt-belt states — factors that led it to conclude the problem wasn’t a defect, even though it could lead to crashes.
“While NHTSA can’t order a recall in this case, there is a safety issue that vehicle owners should address,” NHTSA Administrator Mark Rosekind said in a statement. “Older-model vehicles, often driven in harsh conditions, are subject to corrosion over long periods of time, and we need owners to be vigilant about ensuring they, their passengers, and others on the roads are safe.”
This is how NHTSA plans to push for that vigilance — a snappy web video about the need to wash your car:
After 2007, GM and other truck makers changed their truck brake lines from metal-coated to a plastic outer shell that was 50 times thicker and far more resistant to rust. So far, NHTSA has not found anything like the level of complaints in new trucks as it did with the older models.
GM, which issued 84 recalls covering 30.4 million cars and trucks worldwide in 2014, maintained throughout the probe that brake lines need regular replacement, just like air and oil filters, and has a discounted kit for fixing the vehicles that runs roughly $500. Due to its bankruptcy, the automaker is shielded from any problem that happened prior to July 2009. For owners of these trucks and SUVs, the best advice now is to get them checked, pay for the repair — and maybe get a discount book for the local car wash.
This article originally appeared on Yahoo.