The Washington Capitals cleared customs at Dorval Airport last night and, it was a mere formality. The Capitals had taken nothing out of Canada.

In their 30th foray north of the border, the Capitals were squashed by the Montreal Canadiens, 5-0, as Ken Dryden recorded his 41st career shut-out. That gave Washington 28 losses and two ties in Canadian arenas over four seasons.

The Capitals at lease were not humiliated, as they had been in their home rink Friday night by the New York Rangers, 11-4. Despite minimal sleep, the Capitals skated hard and, except for a couple of unwise first-period violations that set up Montreal power-play scores, it might have been more interesting to television fans watching throughout the United States and Canada.

An oil leak on the Capitals' original charter plane Friday night forced the summoning of a replacement from Sarnia, Onterio. So the Capitals, who reached Baltimore-Washington Airport at 11:45 p.m., waited for three hours before takeoff and were not in their Montreal hotel until 5 a.m.

Adding to their discomfiture was a one-game suspension visited on defenseman Gord Lane, for leaving the penalty box to join a Friday night brawl. At least his damaged right hand revealed no broken finger bones, so he will be available for tonight's 7:30 Capital Centre contest against Detroit.

Guy Charron twisted his left knee when he was hit in the second period by Bill Nyrop. He is expected to play today but probably will not be at full speed.

With Lane in the press box, the Capitals were reduced to five defensemen, a precarious situation against the pressing Canadiens. Still, it was obviously not the defense that should be blamed for the team's sixthe shut-out defeat of the season.

Except for an occasional sortie by Montreal natives Guy Charron and Bob Sirois, the Capitals' good scoring opportunities could be counted on one hand. There was a long shot by Gerry Meecham in the first period, on which a screened Dryden happened to be in the right place, and a third-period situation in which Bill Riley, freed in front by Rick Green setup, drove the puck through Dryden's pads only to have defenseman Guy Lapointe clear it from the crease.

Montreal, meanwhile, was keeping Jim Bedard under intense fire, particularly in the first and third periods. The only goal the Canadiens needed to win came with Washington's Robert Picard off for hooking Steve Shutt. Yvon Lambert rebounded a Guy Lafieur shot at 9:48 of the first period for his 16th goal.

Green fumbled a long pass by Montral's Mario Tremblay, permitting Shutt to gather it up and beat Bedard on a breakwaybackhander at 12:03. Then, at 19:18, with Picard again sitting in the box, for interference on Doug Eisenbrough, Shutt drilled his 44th goal into the far corner from the left-wing circle. Bedard, well out of the net, made the right move, a left-foot kick, but a shade too late.

Doug Jarvis' deflection of a Larry Robinson slap shot and Tremblay's deflaction through Bedard's legs of a Pierre Larouche centering pass closed the scoring in the third period.

Lafleur's lone assist boosted his point total to 125, the third straight season he has reached that milestone. He also had the crowd of 16,896 buzzing with some superb passes and with some remarkable puck handling. He slid the puck through Picard's legs on one occasion to set up a breakaway that Bedard foiled and his long cross-ice pass freed Shutt for a shot that Bedard blocked while skating into the right-wing circle.

Yvan Cournoyer was a frustrated Canadien in the final period. Shooting on a two-on-nobody break, he struck a goal post. Another time he held the puck with Bedard out of the net, flipped it over and watched Rick Bragnalo make the backup save. Finally, after stealing the puck from Green, he shot stealing the puck from Green, he shot wide on a breakaway.

The Canadiens' fans gave Washington's pesky Bryan Watson a tough afternoon, vocally, but he shrugged it off, continued to bang into the bigger Montrealers and, to show his disdain, on one occasion used his stick in pole vault fashion to leap into the players' bench.

Washington Coach Tom McVie was proud of the way "the hockey club rose to the occasion after those two blastings at home." He was not upset about the scheduling, saying, "It's not tough. Life is tough, marriage is tough, going to Vietnam is tough. Compared to the minors, this is easy. Down there, if the bus driver was sick, I'd drive the bus. Conditions here are great."

The Canadiens have now won nine in a row, longest winning streak in the NHL this season, and have lost only two of their last 43 games. They are 23-0 against Washington. That adds up to a big edge.

Washington has lost four in a row, given up peight power-play goals in three games and generally deteriorated to the point that it can envision only one positive item - the No. 1 choice in the upcoming amateur draft.