I took my 6-year-old EL to Krown for it's first application recently. I had the tech put it on the hoist first, and took a good look around. No rust yet, so, spray. There's no Krown warranty for such an old car, but I'm not interested in one. I just want to delay the rust a few more years. I've seen these cars look great for 6 or 8 years, then strart rusting at the bottom of the door panels and behind the wheels.
Yes, it drips for a couple of days. Yes, you have to deal with a sweet, oily smell during that period. Yes, you'll have some oil leak out onto windows and the paint. So what? Wash your car.
By all accounts, Krown has the best product on the market. But since the body shop is giving you yearly applications for free, I'd be inclined to take them up on the offer.
Personally, I'll probably Krown the EL every other year until I sell it. In between, I have a spray bottle of the stuff I can apply to problem areas.