It's usually better just to wash it frequently, including the undercarriage. Aftermarket rustproofing can easily do more harm than good by plugging up drain holes that should be there and creating new places for water to get in.
I own a place in MT. SNOW, VERMONT. Any rust issues to worry about with the PRIUS from salt on the roads?
I've never seen a rusty Prius but only time will tell if they are prone to rust. Obviously salt is never good but I think rustproofing is a bit of a scam. I second the advice to wash the car when you get a break from freezing temps and treat any dings and scratches when they happen.
I am a firm believer in the rubberized undercoating, especially since I live in MN. They had a packaged deal when I bought mine, so I had it done.
When I lived in MN, the rustiest rust buckets were the cars with rustproofing stickers on them. Rustproofing clogs drain holes, and is a waste for plastic areas! Spend that money on weekly car washes, instead. Generally, most areas are using less salt, anyway, due to environmental damage.
I had mine rust-proofed with Krown, an oil spray recommended by CAA (Canadian AAA). I'm a believer in this specific product and company only. Never did it to my last car, and it still looked good after 14 years, but it rusted out some components and thus cost me money. Wifes car is the same. I'm supposed to reapply every year for $100, but I may skip every 2nd year. I'm hoping my Prius lasts 20+ years. If you think you will sell within 5-7 years or so, it may not be worth it, IMO.
Wait a minute, you're supposed to be enjoying Vermont now instead of sweltering in Ft. Pierce. You should go to Florida when Vermont has ice and salt on the roads.
To the OP. Ya know.... I've spent a little bit of time in the wheelwells and under the rear end of the car since 2 months, and already I find Toyota weld points poorly painted such that they are rusting. Yes, rusting, albeit small, for now. I also noted the same on suspension items. I saw an undercarriage paintjob that, on my car, must of been applied by the robot that ran out of paint as it traveled down the conveyor, or it was dipped in a low pool. For my car, not for yours, I think I may look into some form of undercoating. Why me? ZC1
Strangely enough the warranty the rust proofing companies give is about the same as the manufacturer gives these days. I think you get 5 years against rust.
That's true, but if you live in a salty winter environment, Toyota's five year rust warranty is voided, the rust proofing companies still give the 5 years.