Three-time F1 champion Stewart is a long-time critic of FIA president Mosley
Sir Jackie Stewart fears the scandal surrounding world motorsport boss Max Mosley could damage F1 financially.
The News of the World has again claimed that Mosley took part in a "Nazi-style orgy in a torture dungeon". He denies his actions had any Nazi connotations.
F1 great Stewart said Mosley's conduct could deter new sponsors and lead to existing ones quitting the sport.
"You are talking about multi-national corporations, and what's going on right now could damage them," said the Scot.
"If you were such an organisation and the chairman or CEO was excited about coming into F1, the marketing director might say 'there's a lot of stuff going on at the moment, why don't we hold back until we see how they handle it'.
"The sport is vulnerable when it comes to moral issues. If it's called a 'scandal', that affects F1 as a whole and the perception of it by some cultures and religions."
Three-time world champion Stewart, who has clashed with Mosley over many issues in the past, said current sponsors could start to get itchy feet if the situation drags on.
It's more to do with Mosley saying 'I'm going to have to step down', than the FIA having to vote
"Many sponsors are tied in contractually, but the problem is if those contracts are coming up for renewal, they might be unhappy the sport has been blemished."
Stewart reiterated his call for Mosley to quit, adding: "If he was chief executive of the FA or International Olympic Committee, he would have already stood down."
Sunday's News of the World contained fresh allegations about Mosley, who insisted in a recent letter to motoring bodies that he had "done nothing wrong" and that his actions were "harmless and completely legal".
The newspaper rejected Mosley's claims that it had misrepresented the incident and said it would send its videotapes to the FIA Senate and make them available any of the national authorities that make up the organisation.
Stewart criticised Mosley for calling an extraordinary assembly of world motorsport's governing body, the FIA, to discuss the issue.
For logistical reasons, it could be well over a month before delegates can meet in Paris - and that is too long to wait, he said.
"By then we will have had Grands Prix in Spain, Turkey, Monaco and Canada, and I don't think he can hold on for that long.
"It's more to do with him saying 'I'm going to have to step down', than the FIA having to vote."
Mosley is taking legal action against the News of the World and seeking "unlimited damages".