Punsters like to refer to PBS as the ''Petroleum Broadcasting Service'' because so many of its funders are oil companies.
A look at the list of 170 corporate funders reveals not only oil companies but corporations in just about every area of the American economy - from J. C. Penney to the Polaroid Corporation.
But of the top 12 funders, all of which underwrote more than $1 million worth of programming in fiscal 1982, eight are oil companies.
PBS officials report that corporate America seems to be on hold in regard to funding. Most companies are keeping up their participation, but not increasing it this year.
What is corporate America's reason for underwriting Public Broadcasting Service programming? A chief reason is prestige. Corporations chipping in money for public television often take on the quality image of the network itself. Other companies are looking for a different audience than commercial TV's. For many firms, commercial television is the place to make the hard-sell pitch, but PBS is the place to polish an image.
Two of the top PBS funders - Exxon and Mobil - have only recently indicated that, although they buy time on cable and commercial TV, their major commitment is to PBS.
''We feel that our participation in 'The Magic of Dance' will serve the twofold purpose of doing something worthwhile and at the same time polishing our image,'' said Philip L. Thomas, vice-president of corporate communications for Esmark Inc., a diversified holding company that recently went through a name change.
''We are underwriting the Dame Margot Fonteyn 'Magic of Dance' series because the programs speak to upscale, well-educated people who buy securities.''
Other corporate officials say they can reach an audience more suited to their product through public television than over the commercial channels. ''We believe PBS to be a sound alternative to commercial TV,'' said Edward F. Beckwith, vice-president for contributions and civic affairs at CIGNA Corporation, the new corporate name for a merger of two insurance companies. He adds that the company is developing new market strategies to help create a ''national image for a new company. PBS is part of that plan.''
John Madigan, vice-president of communications for the Chubb Group of Insurance Companies, says that ''it gives us the right kind of identification with the public.''
There is some good samaritanism in corporate support of the Seseme Streets, Novas, and other programs on the public airwaves, of course. By backing a program, the corporate community believes it is providing a public service. If this reaps some public-relations capital, so much the better.
''We believe in the kind of alternate programming that PBS brings to the American public, more so than commercial television,'' said Thomas Latimer, senior director of advertising and corporate communications for Gulf Oil Corporation. ''We would hope that the public, which is aware of Gulf bringing this kind of quality television into their homes, would think better of Gulf because of that.''
Herbert Schmertz, vice-president of public affairs for Mobil Oil Corporation, is more circumspect. ''I have no idea what we gain - I guess the satisfaction that we are helping public television gain a larger audience. Audiences get something on PBS they don't get elsewhere.''
The man who may know best why corporations underwrite public television programming is Lawrence Grossman, president of PBS, for years an advertising executive. He told the Monitor: ''The image of what they are, the esteem in which they are held, is enhanced by their participation in public television. It's in their own selfish interest.''
''PBS shows attract high-quality workers to the company, make opinionmakers think highly of underwriters, publicize new names, attract investors. We gain by it but so do the underwriters.''
Many in the corporate community are divided over whether commercial advertising should invade public television. Some believe it would only mar PBS's distinctive character. ''I think it would be a serious error,'' said Gulf's Latimer. ''Commercials on PBS ruin the rationale for public television. You would wind up having a fourth commercial network.''
On the other hand, a few commercials would allow the viewer to run to the refrigerator for a snack before watching the second act of ''The Shakespeare Project.'' ''If commercials were done with style and restraint I would say OK, because I'd rather watch a couple of commercials than somebody on his knees for a half-hour begging for subscribers,'' said Mr. Thomas of Esmark.
''It will be tough to pull off profitable advertising on PBS,'' added Mr. Madigan of Chubb insurance. ''Maybe it has to be tried because more money has to come from somewhere, but I would hope it will be a last resort.''
Therein lies the tradeoff. If it comes down to a choice between extinction for what they see as a quality programming network or commercials, many would rather see a few ads. ''If it is collectively decided that PBS needs high-quality, corporate advertising to stay alive,'' said Mr. Beckwith, ''we would support their position on the basis that the pros of their high programming standards would outweigh the cons of selective advertising.''
Top corporate funders of PBS in 1982 Company In millions 1. Exxon Corporation $5.5 2. Mobil Corporation 4.5 3. Chevron USA 3.5 4. Gulf Oil Corporation 1.9 5. Atlantic Richfield Company 1.8 6. Shell Companies Foundation Inc. 1.3 7. Sun Company Inc. 1.2 8. Texaco Inc. 1.2 9. American Telephone & Telegraph Company 1.1 10. Pepsi-Cola Company 1.1 11. First Interstate Bank of California Foundation 1.1 12. General Motors Corporation 1.0 Figures represent spending on production costs only