If you’ve searched for clarity on whether undercoating is safe for hybrids or EVs, it seems there’s a lot of disparate information out there, and not much for conclusive objective data. Here’s my take on the subject.
First, it’s a small sample size, but I’ve coated hybrids and EVs (Prius, Land Cruiser 250, Fiat 500e) with wet film lanolin products (Woolwax, and in recent years Surface Shield) and haven’t seen or heard of any problems on return visits for recoating on any of them.
The three main concerns
From what I’ve read in the course of some research, concerns have come down to a few main things: clogging vents, obscuring orange colored cables/connectors, and damaging rubber/connector seals. I’ve seen mention of concern about voiding warranties or mechanics/dealerships refusing services because of some of those things. Here’s my take on all three, and why I’m pretty confident there should be no problems with the wet film lanolin product and application method I use.
- Clogging Vents: Dry-on coatings - especially thick rubberized products - could be more problematic for filling or clogging small vents. I spray wet film lanolin, which is a thinner oil coating applied as a mist spray. This means there would be virtually no effect on clearance of vent openings, particularly with careful method of application (e.g. I’m careful not to spray too close or too long to load up a ‘puddle’ of oil, especially around vents, weep holes, or electrical connectors). On hybrids, I keep it off the battery pack and its cooling vents. On EVs where much of the underside is commonly covered by large flat shields, I coat any metal shield parts and fasteners and skip plastic shields (no benefit to coating plastic). In any case, I avoid over-spraying or loading up any vents.
- Obscuring orange cables/connectors: Most hybrids and EVs use orange as a conventional color to indicate higher than usual voltage cables/wires in the vehicle. Here especially, the clear wet film lanolin product I use has little to no risk of causing this issue. There is a black version of many wet film lanolin coatings which would obscure more than the clear version, but any wet film (which stays wet and oily) could be wiped off easily. Dry-on black coatings - paint or rubberized - would have potential to obscure in a more permanent, hard-to-remove way that could be problematic if a mechanic took issue with it.
- Damaging Rubber/Seals: Wet film lanolin can affect soft rubber like weatherstripping, where it can soak in and cause some expansion and rippling. Generally, other rubber is unaffected as far as I’ve seen, including gaskets, bushings, and the silicone seals in electrical connectors. I don’t usually spray up in door jambs where it would get on weatherstripping, so I’ve never seen or heard of any effects of coating on vehicles I’ve worked on. And I’m careful not to load up around electrical connectors, which generally have their seals protected inside of the plastic plug housing - likely little to no exposure anyway.
Bottom line
I can’t guarantee there aren’t other potential issues - those are just the ones I’ve been aware of - but can say if/when I get a hybrid or electric car of my own I’ll be coating it with Surface Shield. For all of the reasons mentioned above, I’m pretty confident there would be no issues. Also, the risk of rust and corrosion here in the salt belt appears far worse to me anyway.
Checking with your dealer
If you’ve got a new vehicle, dealer warranty considerations, or just want to be thorough about specific manufacturer concerns, one thing you could do for further peace of mind before deciding is talk to your dealership and ask if they’ve had any issues, or if they have concerns about warranty coverage or anything else. One caution on that front as well, I know some dealerships offer undercoating service when they sell vehicles. That is often something like a Ziebart or other rubberized, dry-on coating, which I generally recommend avoiding completely. See this article on my website for details on that front.
So if they say something like they would only allow a dealer applied undercoating, I would rather have no coating than get a dry-on rubberized coating. Or if they say that they would avoid any undercoating, but that’s based on assumption of a dry-on/rubberized product, it may be worth follow-up questions or further consideration for a wet film product.
What I’d do with a new vehicle
Personally, if I bought a new vehicle I’d put wet film lanolin on it right away. You can read more details about why in this article, including a link to a 7-year A/B test of similar trucks uncoated vs coated with wet film lanolin from brand new. Spoiler alert - here’s a comparison photo - very clear, near-perfect rust protection with the coating:
Have a hybrid or EV you’d like to get coated before the next round of winter road salt rolls out again? Details and pricing are on my undercoating service page, or get in touch to schedule or ask any specific questions.