PROVIDENCE — He sees it as the realization of a dream: to have traveled from coast to coast with his wife and family in a luxury motor home running on little more than the used fat from America’s restaurants.

When Steven and Anke Adler, along with their children, Lilly, Julia and Jonah, pulled up to their home on Hillside Avenue two weeks ago in a 40-foot-long motor home made to run on vegetable oil, it marked the culmination of a 78-day adventure that, despite its scary moments, is one they say they would do again in a heartbeat.

“We know there are hippies who have traveled the country in old school buses running on vegetable oil,” says Steve, “but I don’t think anyone has done ever done it with a luxury motor home with this kind of on-the-fly filtration system and a 50-foot retractable hose that lets you cruise indefinitely and refuel at your whim.”

The Adlers’ last oil fill-up on the way home from Seattle was at a Chinese buffet restaurant in Chicago, where they took on enough vegetable oil — 140 gallons in the main tank and 58 gallons in their filtration tank — to get them back to Providence using only a small amount of diesel fuel and no gasoline.

Just a year ago, Adler, a 40-year-old computer specialist and consultant, made news when he converted his 1991 diesel-powered 350 SDL Mercedes to run on used vegetable oil, saying that if he was going to ride in a car that didn’t need gasoline, he might as well as get a big, luxurious car that “even the rich people” would envy.

He says that had it not been for his experience of converting the Mercedes — and finding out that it actually runs more smoothly on vegetable oil — he would not have dared to take taking his family to the West Coast for what seemed like a crazy quest.

He began begun by calling Chris Goodwin, the Seattle man who developed the conversion kit that he had installed last year, to ask if he’d be willing to help him convert a motor home. After getting a tentative yes, he searched the Internet and found just the kind of vehicle he was looking for.

The Love Bus, or “El Bee” as he and his wife affectionately call it, is an enormous vehicle, custom made by the Blue Bird bus company. The size of a 57-passenger bus, with lots of storage space in the luggage area, it listed for $440,000 soon after it was made in 1997, but was selling on the Internet for $150,000 when Adler saw it on eBay. He got the price down to $106,000 and bought it from a dealership in Junction City, Ore., sight unseen, taking out a 20-year mortgage to do so.

But the real adventure, and gamble, came on July 12 when Adler flew his family out to Oregon on one-way tickets to pick it up. El Bee, it turned out, was quite a sight. Formerly owned by a corporation in Louisiana whose owner apparently liked entertaining guests at NASCAR races, it came with a reinforced steel roof strong enough for a crowd to walk on and party. It also has a queen-size bed, a sofa, a glass shower big enough for two people, a huge refrigerator with an icemaker, a stove, microwave, and a $1,200 washer and dryer, and lots of expensive cabinetry.

Down below, there was an extra axle to help carry the vehicle’s 22 tons.

But there were shortcomings, too.

“When we picked up the thing, there were so many things wrong with it we couldn’t leave for several days,” Steve recounts. The toilet was leaking. Fluid was coming out from the front, and the generator was overheating.

Steve and Anke had to wait three days for the dream vehicle to be fixed. It was around that time when Steve says he began to get “a little bit freaked out.”

“I said to myself, ‘What am I doing here? So many things could go wrong.’ I didn’t know if it would run. I didn’t know if this guy in Seattle would be able to do the conversion. Though he said he’d do it, he wouldn’t give me a firm date. And I had no idea how much it would cost.”

HIS WORST fears seemed to be realized when they arrived at Goodwin’s shop in Seattle, only to be told he wasn’t ready and that he should come back in two weeks.

So what does one do with two weeks extra to hang around? The Adlers, on Goodwin’s advice, parked their “bus” in a marine terminal and freight yard.

“It was horrible. We were out of water and there were no shops around where we could get water,” Anke a remembers. “We couldn’t wash up or go the bathroom. And there were freight trains, very long freight trains, going by all night. We were 3 three feet away from the tracks.”

Steve says it was one of his worst nights as well. “I started freaking out. My children were thousands of miles from home because of this crazy vegetable idea. What had I done to them? Anke had to slap me down. That was a bad moment.”

Perhaps at some other time or place they would have gone to a motel. But there was a big convention in town, and every place in and around Seattle was booked. They had no choice but to stay in their “bus.” The next day, they drove El Bee down to Oregon to finish their wait.

“Steve had to attend to his business, so he would stay back in the bus working on his computer while I took the children to see all the sights,” Anke a says.

Two weeks later they returned to Goodwin’s shop. “I’m sure he was secretly hoping that we would have given up and headed back east,” Adler Steve said. “But I warned him, ‘I’m a crazy man, and we’re not going to leave so easily.’ ”

The couple says Goodwin was stand-offish at first, but in the end proved to be quite generous. Goodwin, who Steve calls an inventive genius who once worked as a photographer for National Geographic, put the rest of his conversion-kit business on hold as he and his two workers threw themselves into the El Bee project full-time.

It was a complicated project, much more complicated than the conversion of the Mercedes, since it the project involved building a complete system whereby over the course of a day newly acquired waste oil could be put through a filtering process while the vehicle was cruising, so that by the end of the day the water and unwanted residue could be flushed out, leaving only the good oil.

Since the workers had to work on a generator located under the queen-size bed that the children used, the family had to leave the bus during the day. Since the shop was in the city’s Capital Hill district, in an area where people were shooting heroin and exchanging needles 50 feet away, the Adlers knew they had to get their children away.

Says Steve: “It was a scary neighborhood.with men with beards and dresses constantly walking by”

GOODWIN AND his family developed a warm relationship with the Adlers, to the point where the two families would go to the beach together on weekends. Goodwin also gave them the keys to his car during the day, so they could get around during the day, and gave them another car after that one was stolen.

Initially, Goodwin thought they’d have the project done in a week. But then the project stretched to two weeks, then three. Anke said she took it in stride. “Every Monday he’d say, ‘You’ll be out of here by Friday.’ But I knew we wouldn’t.”

In fact, it was a six-week project that ended on Labor Day weekend. Steve says that he believes that Goodwin was into the project as much as he was because he realized that this was something unusual and new — the first -ever luxury motor home to run on vegetable oil with its own on-board filtration and de-watering system.

As with the Mercedes, the vehicle has to run on diesel during the first few minutes of operation to raise the temperature so it can run on vegetable oil.

But where does one get such oil? The Adlers used pure vegetable oil purchased from Costco to launch their return home beginning on Labor Day. But a day or two into the trip, they started to take on the waste oil from trash bins at fast-food restaurants in British Columbia, being careful to explain their project to managers. That’s when they hit their first problem. A manager at a Wendy’s was so happy to provide them with oil he got out some extremely hot oil directly from the fryer. It was so hot it melted the Adlers’ hose, forcing the Adlers them to spend the next couple of days days looking for a replacement. They found one in a store that sells hot tubs.

But the bigger lesson came in the discovery that while used oil from Wendy’s and McDonald’s may be fine in a pinch, it tends to have lots of other nasty things mixed in — pieces of meat scraped up from the grill –— that will clog even the most sophisticated filtration system. “That’s when I realized that Chinese buffets are where it’s at,” Adler says. “You may find a wonton now and then, but their oil doesn’t clog the system.”

The older children, Lilly, 8 and Julia, 6,7, were supposed to start class at the Ocean State Montessori School in East Providence on Sept. 6, but the Adlers knew they were never going to make it. So after being advised by school administrators to have them write a journal, they turned the trip into a learning experience.

Anke a bought a couple of Spanish language books and books on lettering and used the time on the road to teach. In anticipation of to a visit to Mount Rushmore in South Dakota, Ankea had them read a book about the U.S. presidents. They visited the Grand Coulee Dam, Yellowstone Park, the Mall of America in Minnesota, and several Chicago museums.

It was in Chicago where they stopped at a Chinese buffet restaurant, coming back for oil twice since they could only take 58 gallons at a time. “All the workers came out to see us fill up, and the owner said, ‘You a winner, I a winner. We are all winners.’ ”

On the way home, Anke cooked prepared sushi, fresh bread and apple pie. The only thing they had little of was cash. They were nearly out of money, their debit card no longer worked and somewhere in Canada their credit card was declined.

As they made their way through New York and found they didn’t have enough to pay the New York Thruway toll, daughter Julia volunteered her tooth fairy money.

Yet they returned home filled with happy dreams.

“I’m not saying we weren’t ready to kill each other many times,” Steve says. “There were some mountain passes where the dirt roads are at a 45-degree angle where you shouldn’t be in a Jeep and where we thought we’d die. But overall we’re closer now than ever. It was an amazingly bonding experience.”

His wife agrees.

“Absolutely, I would do it again in a heartbeat. I would do it tomorrow,” she said. “If the kids didn’t have school, I would be in that bus all the time. I’m telling you, there are a lot of changes when you do this kind of thing. We didn’t know the bus at all, but we got to know it really well, and the limits of what it can do and what we can do.”