Filed by Holly Corporation
Pursuant to Rule 425 under the Securities Act of 1933
and deemed filed pursuant to Rule 14a-12
under the Securities Exchange Act of 1934

Subject Company: Frontier Oil Corporation
Commission File No: 1-07627

		HollyFrontier

Weekly Communiqué #08—Merger Update
May 6, 2011

We hope you’ve had another great week.

Today, our topics are threefold:

	1.		First, Nellson Burns has asked to share several thoughts regarding progress on the IT front.
	2.		Second, having introduced the Cheyenne refinery in last week’s Spotlight, today we are featuring Woods Cross. In a couple weeks, we’ll spotlight El Dorado.
	3.		Third, we have received three more FAQs and are including our responses to them.

In recent weeks, we have been immersed in site visits, application reviews, integration planning, cost analyses and much more. Because technology is a foundational building block for any business—and because we all take our technology very personally—our commitment, of course, is to afford everyone a voice in this process. We wanted to take a few moments today to communicate “where things stand” and articulate a few principles and next steps.

We currently possess an “applications list” for Holly and Frontier. We are using this list to evaluate commonalities, differences and integration opportunities. Some applications are very unique and specialized, in which case, consolidation might not make sense. Others are very expensive and high-use, in which case consolidation does make sense. Some are so critical that our united business would fracture if not consolidated. And all our 3^rd party applications require licenses and/or renewals, which means we want to scope our future needs effectively before making long-term commitments on behalf of the broader organization.

To date, we have been gathering input from key stakeholders across the enterprise, calculating costs, studying business functions and, similarly, application functionality. Recommendations are made to the HollyFrontier Integration Team and, ultimately, Mike Jennings and Dave Lamp weigh-in or approve before we take action toward implementation.

Over the next sixty days, we will be working with our business stakeholders to build and complete an IT Roadmap that captures our project work and denotes the many milestones along the way. It will include strategies and tactics ranging from platforms and development work to collaboration tools, email box sizes and everything in between. Our decision criteria are neither Holly nor Frontier biased but, rather, revolve around associated costs, requirements and best fit for the combined organization.

A number of decisions are behind us, SAP among them. More will be communicated soon as we complete our roadmap. It is safe to say that if you work at a refinery, you will experience less change on Day One than anyone else, because the more centralized, back-office environments are inclined to see the most initial IT unification.

We’ll share more details as they become available. Along the way, don’t hesitate to send the Integration Team your questions via hollyfrontier_merger_questions@hollycorp.com.

Nellson Burns
Vice President, Information Technology, Holly Corporation

Woods Cross Refinery, Leadership

Woods Cross Refinery, Leadership continued

Woods Cross Refinery, Timeline¹

Woods Cross Refinery, Timeline continued

Employee FAQs

Employee FAQs		Integration Team Response
“After the merger, will HollyFrontier add a corporate inspection position to assist and guide the five facilities to share best practices and align procedures? There also will likely be opportunities for cost savings by consolidating resources and programs if someone is in the position to drive the changes.”		Holly and Frontier have several best practices groups, Safety, Environmental, Training, PSM and Reliability Centered Maintenance among them. We intend to continue these and add new groups in the future, as well as explore more systematic ways (both centralized and decentralized) to align the organizations swiftly after close.
“What are the IT policies going to be regarding internet usage, email box sizes, printers, servers, etc?”		These are excellent, tactical questions—and similar to the sort we are hearing more often. Detailed answers to such questions are forthcoming in the weeks ahead, but hopefully today’s communiqué has begun to articulate our initial IT framework and timeline for tackling such items. We can say that Holly and Frontier handle email differently today, including email account size limits, which are typically lower at Holly. Both companies limit internet usage, and that will be reviewed but will continue in some form. Also, we will be moving to a centralized IT support model—so as we collectively decide what applications need to be centralized, servers may be moved to the Dallas Data Center. One key point to remember is that none of this will change on Day One. We will communicate more details as decisions are made.
“How and when will we get new business cards with the HollyFrontier logo?”		As you can imagine, we will need to create entirely new branding collateral (letterhead, business cards, corporate materials, etc.) in preparation for Day One. Once we have selected the logo, we will begin designing such items and distribute them immediately upon close.

Submitting Questions or Suggestions to our Integration Team

For those of you who have questions, suggestions or concerns about the Integration process—or have heard rumors and would like to surface these for a response, you may either submit them to your local HR Department—which will, in turn, share them with us—or you may email the HollyFrontier Integration Team at hollyfrontier_merger_questions@hollycorp.com. Please share what’s on your mind, as we cannot strive to meet unknown expectations or address unshared concerns.

Next week’s communiqué, Merger Update #09, will be provided in an entirely different format. As indicated in prior weeks, it will be a video segment rather than a written document.

On Friday, May 13^th, 2011 we will provide a hyperlinked URL to this video segment which will afford us the opportunity to answer two questions we often hear, “What’s the purpose of the merger?” and “What sort of culture does executive management want to create?”

We will release additional video segments in subsequent weeks that address more questions.

Finally, to all the mothers—you will be in our thoughts this Sunday.

Warmly,

Dave Lamp
President
Holly Corporation

Important Information for Investors and Shareholders

This communication does not constitute an offer to sell or the solicitation of an offer to buy any securities or a solicitation of any vote or approval. The issuance of Holly Corporation (“Holly”) common stock in connection with the proposed merger will be submitted to Holly’s shareholders for their consideration, and the proposed merger will be submitted to shareholders of Frontier Oil Corporation (“Frontier”) for their consideration. Holly filed with the Securities and Exchange Commission (“SEC”) a registration statement on Form S-4 that included a joint proxy statement to be used by Holly and Frontier to solicit the required approval of their shareholders in connection with the proposed merger and constituted a prospectus of Holly. Holly and Frontier may also file other documents with the SEC concerning the proposed merger. INVESTORS AND SECURITY HOLDERS OF HOLLY AND FRONTIER ARE URGED TO READ THE JOINT PROXY STATEMENT/PROSPECTUS REGARDING THE PROPOSED MERGER AND OTHER RELEVANT DOCUMENTS FILED WITH THE SEC CAREFULLY AND IN THEIR ENTIRETY WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT THE PROPOSED MERGER. Investors and security holders may obtain a free copy of the joint proxy statement/prospectus and other documents containing important information about Holly and Frontier through the website maintained by the SEC at www.sec.gov. Copies of the documents filed with the SEC by Holly will be available free of charge on Holly’s website at www.hollycorp.com under the tab “Investors” or by contacting Holly’s Investor Relations Department at (214) 871-3555. Copies of documents filed with the SEC by Frontier will be available free of charge on Frontier’s website at www.frontieroil.com under the tab “Investor Relations” and then under the tab “SEC Filings” or by contacting Frontier’s Investor Relations Department at (713) 688-9600.

Holly, Frontier and certain of their respective directors and executive officers may be deemed to be participants in the solicitation of proxies from the shareholders of Holly and shareholders of Frontier in connection with the proposed transaction. Information about the directors and executive officers of Holly is set forth in its proxy statement for its 2011 annual meeting of shareholders, which was filed with the SEC on March 31, 2011. Information about the directors and executive officers of Frontier is set forth in its proxy statement for its 2011 annual meeting of shareholders, which was filed with the SEC on March 21, 2011. These documents can be obtained free of charge from the sources indicated above. Other information regarding the participants in the proxy solicitation and a description of their direct and indirect interests, by security holdings or otherwise, are contained in the joint proxy statement/prospectus and other relevant materials to be filed with the SEC.

Cautionary Statement Regarding Forward-Looking Statements

This communication contains “forward-looking” statements within the meaning of Section 27A of the Securities Act of 1933, and Section 21E of the Securities Exchange Act of 1934. These include statements regarding the effects of the proposed merger and statements preceded by, followed by or that otherwise include the words “believes,” “expects,” “anticipates,” “intends,” “estimates,” or similar expressions. Forward looking statements relating to expectations about future results or events are based upon information available to Holly and Frontier as of today’s date, and are not guarantees of the future performance of Holly, Frontier or the combined company, and actual results may vary materially from the results and expectations discussed. For instance, although Holly and Frontier have signed an agreement for a subsidiary of Holly to merge with and into Frontier, there is no assurance that they will complete the proposed merger. The merger agreement will terminate if the companies do not receive the necessary approval of Holly’s shareholders or Frontier’s shareholders or government approvals or if either Holly or Frontier fails to satisfy conditions to closing. Additional risks and uncertainties related to the proposed merger include, but are not limited to, the successful integration of Holly’s and Frontier’s business and the combined company’s ability to compete in the highly competitive refining and marketing industry. The revenues, earnings and business prospects of Holly, Frontier and the combined company and their ability to achieve planned business objectives will be subject to a number of risks and uncertainties. These risks and uncertainties include, among other things, risks and uncertainties with respect to the actions of actual or potential competitive suppliers of refined petroleum products in Holly’s, Frontier’s and the combined company’s markets; the demand for and supply of crude oil and refined products; the spread between market prices for refined products and market prices for crude oil; the possibility of constraints on the transportation of refined products; the possibility of inefficiencies, curtailments or shutdowns in refinery operations or pipelines; effects of governmental and environmental regulations and policies; the availability and cost of financing; the effectiveness of capital investments and marketing strategies; efficiency in carrying out construction projects; the ability to acquire refined product operations or pipeline and terminal operations on acceptable terms and to integrate any existing or future acquired operations; the possibility of terrorist attacks and the consequences of any such attacks; and general economic conditions.

Holly and Frontier caution that the foregoing list of risks and uncertainties is not exclusive. Additional information concerning these and other risks is contained in Holly’s and Frontier’s most recently filed Annual Reports on Form 10-K, subsequent Quarterly Reports on Form 10-Q, recent Current Reports on Form 8-K and other SEC filings. All subsequent written and oral forward-looking statements concerning Holly, Frontier, the proposed merger or other matters and attributable to Holly or Frontier or any person acting on their behalf are expressly qualified in their entirety by the cautionary statements above. Neither Holly nor Frontier undertake any obligation to publicly update any of these forward-looking statements to reflect events or circumstances that may arise after the date hereof.