Bob Dudley, BP’s likely next chief, may be a superb diplomat. But the American executive’s roots at Amoco — the oil company BP acquired in 1998, and which has been the source of most of its safety problems — make him a less than ideal choice to reform BP’s flawed corporate culture. A fresh hire from outside arguably stands a better chance of transforming BP.

At first blush BP’s expected appointment of Dudley, as soon as Tuesday, looks like a break with tradition. As successor to Tony Hayward, Dudley would be the first non-British CEO at the former government-owned company. And with his southern drawl and calm confidence, the Mississippi native is well placed to repair BP’s shattered relations with Uncle Sam. Placating U.S. anger over BP’s Gulf of Mexico fiasco is BP’s most pressing task. Being squeezed out of growth opportunities in America — where it is the largest domestic oil producer — threatens the firm’s independence.

But there is more to the job than glad-handing lawmakers and officials. The new chief’s task will be to succeed where Hayward failed, in restoring BP’s reputation for technical competence and high safety standards. A root-and-branch reform of the firm’s procedures will be needed, along with incentives for staff to comply with them.

Anointing another insider who rose through the ranks under former boss Lord Browne — while at the same time perhaps reshuffling Hayward, rather than cutting ties with him — raises doubts about BP’s desire to reinvent itself. Dudley hails from the most accident-prone quarter of BP’s empire, joining Amoco in 1979 and rising to head of group strategy.

Indeed, it was from Amoco that BP inherited the Texas City Refinery, where 15 workers were killed in a 2005 blast. Long before BP’s takeover Amoco’s safety record had been tarnished, notably by the 1978 Amoco Cadiz tanker spill, the largest of its kind at the time, and a fatal 1980 chemical plant explosion in New Castle, Delaware.

Of the internal candidates, Dudley was surely the politically shrewdest choice. And it’s true that a newcomer would struggle to rapidly understand BP’s maze of businesses — one reason that most big oil companies like to promote from within. But with BP’s long-term survival hinging on a profound cultural shift away from its corner-cutting past, now might have been a good time to depart from this industry custom.