Tighthead Oosthuizen sustained the injury in the second half of the match at Perth Oval and will return to South Africa to see a specialist in Durban.
The uncapped Louw, 23, is another hefty tighthead who has impressed with the Stormers in Super Rugby and represented South Africa "A" in their victory over the French Barbarians in Durban in June.
Despite the disappointment of failing to convert pressure into a winning score at the end of the Perth test, the Springboks will travel to Auckland for next week's clash with the All Blacks in good spirits.
The draw extended their unbeaten run to six matches this season and a victory over the world champions at the North Harbour stadium next week could send them top of the Rugby Championship standings with two home matches remaining.
A reflection of their new-found confidence came when coach Allister Coetzee, who oversaw losses in eight of 12 tests in 2016, said the team would not be happy with a draw even away from home against the twice former World Cup winners.
"We did enough but unfortunately I think the first half, just the discipline cost us a bit, conceded unnecessary penalties which gave them opportunity," he said.
"We'll look at that and try to be more clinical."
Coetzee said the Springboks were benefiting from renewed collaboration between the national team and the South African Super Rugby franchises over conditioning but were still well behind New Zealand in such areas.
"The All Blacks could have shifted gears in the last 10 years because they have been working together as a nation to make sure their conditioning is right up there," he said.
Argentina, who the Springboks beat home and away to open their Rugby Championship campaign, led the All Blacks at halftime on Saturday before succumbing 39-22, which offered Coetzee some encouragement.
"It will be a hell of a battle and they're still the best side in world rugby," he added.
"Argentina showed today that when you're accurate and you apply pressure in all the areas of the game, you can take them on."
(Reporting by Nick Mulvenney, editing by Ian Ransom)
