The flat-finish California 2010 paint looked best overall after years of exposure in Consumer Reports' tests.

Consumers could spend several dollars more per gallon for exterior paint and stain this year, thanks in part to the pricier petroleum that goes into them. That might tempt shoppers to pick a lesser-grade coating. But Consumer Reports’ recent tests show that penny-pinching could cost more money over time.

Manufacturers reformulate their products often, typically to meet rules limiting volatile organic compounds. But they admit it’s a challenge to reduce those pollutants without compromising performance. CR’s latest fully tested paints did not fend off dirt and other weathering effects for as long as some past products.

Because reformulated finishes might not wear the same as earlier versions CR removed all such previously tested products from the ratings. That’s why a few familiar brands, including some of last year’s top scorers, are not included. But there are several new picks from Valspar and other brands with durability and value.

CR’s latest ratings of more than 40 paints and stains include results for major brands after a year or two of accelerated outdoor testing, equal to about three to six years on a house. But as the scores show, some initially promising finishes look far less impressive after the equivalent of roughly nine years. The tests also showed that some lesser-known paints looked better than some heavy hitters and some stains needed to be reapplied after the equivalent of only three years.

Of the paints CR fully tested – that is, those that completed the equivalent of nine years’ exposure – California 2010 (flat) ($38) topped CR’s ratings, followed by Kelly-Moore Acry-Shield (flat) ($32). For stains, Olympic Premium 596xx (latex) ($21) topped the ratings of those that were fully tested.

Here are other findings from CR’s tests:

¢ Smaller brands take the top. California brand paints have long been top performers in CR’s ratings, and the 2010 line is no exception. The regional brand’s Fresh Coat Velvet flat finish, previously CR’s top pick, is also doing well in its retest after the equivalent of roughly three years in the elements. Kelly-Moore, another regional brand, joins California’s 2010 at the top of this year’s ratings of fully tested paints with its Acry-Shield flat.

¢ The dirt on some big brands. Some versions of Kilz, sold at Wal-Mart, had trouble keeping clean after the equivalent of six years, while several from Ace, Behr (a Home Depot brand) and Benjamin Moore needed cleaning after the equivalent of only three years. Of the two Valspar (Lowe’s) Ultra Premium Duramax paints still being tested, the flat is doing better so far at keeping its original color.

¢ Opaque stains are clearly better. Opaque stains save time and money in the long run because they outlast semitransparents as a group. Pluses for semitransparent stains include visible wood grain and less prep work, because those stains penetrate the wood rather than forming a top film like opaque stains. But even the best opaque stain won’t last as long as most paints, all of which resisted cracking in CR’s rigorous outdoor testing.

How to choose

¢ Match the paint to the locale. Look for mildew resistance for homes in a cool, moist or shady climate. Dirt resistance is more critical in urban and industrial areas, and resistance to color change is important in sunny locations and climates.

¢ Know what the pros are using. A painter’s top choice might not be a top pick in CR’s tests. Make sure that the written contract clearly states the brand, line and cost of the paint or stain used.

¢ Look for hidden savings. It’s often possible to cut paint costs by 50 percent or more by buying two five-gallon containers instead of 10 one-gallon cans. But resist the urge to choose a lower-grade paint to get the larger container.