Hi everyone,

I just picked up a G37x coupe, so I just joined the forum. I would like to do an undercoating on it. I really don't want to do the oil undercoating every year. I've looked around online, and read about POR 15. Anyone have any experience with it on their G? Or suggest something better?

Cheers

 

Many people who restore antique cars have the undersides sprayed with bedliner. The undercoating that they put on cars years ago has been outlawed, I believe it had asbestos fibers in it.

My best advice is do not do it. If you're concerned about rust, have the car washed as soon as practical after driving on salted roads. I know of no effective undercoating and the factories do a pretty good job of applying rustproofing at he factory. Some undercoatings actually make things worse.

 

Leave it alone.

 

seriously? Leave it alone?

That's what I did with my last coupe, and floor and frame rotted away to a point where it was no longer safe to drive. The body looked mint and the engine only had 100k miles on it...

 

Did you never wash it? I find it hard to believe any decently maintained car would just rust through with 100k miles. Also, if your signature is right and you bought a 2009 I think it'd be a little late to prevent any rust.

 

Yes of course I washed it, but being in Canada and having to deal with tons of salt in the winter and freezing temps doesn't always mix well. I wasn't taking it to the drive thru car wash every day in the winter, and certainly wasn't going spray the underside at home on frigid days either.

Undercoating is a big business in Canada, most people I know settle for having the oil treatment done under their car every year. Yet their cars still rust. My '73 Fastback had a quarter inch of tar applied when new, and 31 years later there was not even a hint of rust with the exception of the exhaust and brakes.

That's why I was looking at POR 15; tar will hold in the moisture, and if you have any rust, it will just get worse. From what I understand POR 15 and it's prep process neutralize rust, then prevent more. So far the underside of the G looks pretty clean, I just want to keep it that way.

 

POR15 is a pretty good paint. I wouldn't call it undercoating. I don't see any harm with touching up the rusty spots every spring. POR15 doesn't stand up to sunlight though. It cures by reacting with the moisture in the air. If you have a tiny amount of moisture trapped between panels it will actually suck it out of there.

POR15 has been used by the restoration folks for years.

 

Ah my bad. I'm used to winters in the Midwest where you only see those conditions for a handful of months tops. POR 15 seems to have good reviews, never used it personally though.