MERGING with a larger competitor.

BIG OIL WAS GROWING bigger in 1998.

Seeking to boost its bottom line, British Petroleum PLC spent more than $52 billion for smaller rival Amoco Corp.

Industry observers scrutinized the deal, poring over details such as the combined company's production capacity, market capitalization, and global reach. But what sticks in the mind of Bill Lowrie, who served as a deputy CEO for the merged companies, was less obvious but equally critical: the different structures at the two firms.

Lowrie, Amoco's president before the merger, got to see first-hand the differences at the two companies. He spent the better part of a year working on the merger's details as he shuttled between Amoco's headquarters in Chicago and BP's central office in London.

While Amoco executives oversaw clearly defined business units, BP managers were expected to work in a group, across divisions. The differences concerned some at Amoco, including Lowrie, who wondered what would happen to their positions in the merged company.

Once BP and Amoco merged, Lowrie was named codeputy CEO along with another BP executive. Lowrie was to oversee the chemicals, refining, and marketing divisions and report to CEO Sir John Browne. But after a few months, he found the co-deputy CEO position unworkable.

Lowrie and other executives had to determine how the merged company would set up performance plans, project evaluations, and compensation schedules, but there were too many executives trying to do the same tasks. "I think you find yourself getting in each others' way," he says.

Lowrie, whose career with Amoco began in the Louisiana oil fields in the 1960s, decided to retire at the age of 56. He insists he has no ill feelings surrounding the merger or his decision to leave.

"I don't think co-whatever you want to call it works well," he says. "Just get one person and get on with it. That's the way I looked at it."