However, there was still potential for competition to be lessened.
"The 49 per cent [market share] is something that sticks itself up as a flag and says the authorities need to look at it," Bodger said.
He said Gull, which operates more than 60 stations and has a roughly 6 per cent market share, may make a submission to the commission on the acquisition.
Z already has 210 service stations and 92 truck stops, while Chevron NZ has 146 Caltex and Challenge service stations as well as 73 truck-filling sites.
The purchase, which also requires Overseas Investment Office approval, includes a two-million-barrel oil inventory, 10 terminal assets and Caltex's lubricants business.
It will be funded by existing cash, debt and a $185 million pro rata capital raising that Z intends to carry out after it has received the commission's clearance.
Z shares closed at $5.93 on Friday, below the record $6.20 they reached following last week's news of the Chevron deal.
The firm is aiming to settle the purchase by November 30.