Getting ready to spray-paint my boat trailer sometime in next couple of days. Prep work is almost finished. I'm using a siphon-feed spray gun with a 30 gal. compressor. I'll be using Valspar Anti-Rust which is very similar to Rust-Oleum. I have sprayed before but many years ago. I know if spraying, thinning should be done. Would someone know approx. what ratio of paint-to-thinner would be a good starting point? I sent Valspar an email, but they said they could not make a recommendation due to EPA regulations.<br /><br />NOTE: oops, wrong forum, could someone move it to Trailers. Thanks.