The change was made to the company's Rating and Premium Plan on March 10.

It gives shareholders the option of purchasing coverage on a flat premium or "fixed cost'' basis.

Previously, all premiums contained an element of costs, which was retrospectively rated based on individual loss experience.

Several OIL shareholders have already converted to the new option, according to Mr. K. Doyle Stephens, OIL's president and chief executive officer.

He said many of the company's members are now evaluating the new option.

He described the new option as "probably one of the most significant changes in the way OIL conducts its business since the company began operations in 1972''.

The introduction of flat premium insurance is part of a drive by OIL to make the company more attractive to existing and prospective members.

"It has been apparent that many of our policy holders have chosen to insure their potential OIL retro obligation in the commercial market since the alternative of retaining the retro obligation was not financially attractive.

"Unfortunately, in recent years, the availability of this type of insurance in the commercial market has been diminishing while the cost of the coverage has increased dramatically.

"Since many members view both OIL coverage and retrospective premium protection insurance as a package, we saw the opportunity to provide our members with the ability to purchase the combined coverage from OIL on a very cost effective basis,'' said Mr. Stephens.