Findlay, Ohio,
07:36 PM

Blog: 10 Grammar Mistakes You’re Probably Making Every Day

Editor's note: This article is published as part of a recurring series spotlighting unique roles and organizations within the company. For information about the Public Affairs organization and other career opportunities at Marathon Petroleum, please visit


Last year, an announcement made people very upset. This earth-shattering news seemed to contradict years of wisdom, so it was to be expected that there would be near-riots on the streets. What was the news? In the Associated Press Stylebook, the word “over” is now an accepted way to refer to a quantity (as in, “over 2,000 barrels,” instead of only “more than 2,000 barrels”). Who were the people wanting to riot? The same people who proofread documents, articles, presentations, and speeches for a living.

Grammar rules are a moving target. From school, most of us have the basic rules figured out. We might have a functioning knowledge of the MPA or APA writing styles from term papers, but even those guides tend to only dictate references and overall structure, as opposed to providing practical guidance on sentence structure, word choice or where to put that stupid comma.

At Marathon Petroleum Corporation (MPC), we use the Associated Press Stylebook as our writing standard. Administered by the Associated Press (AP), the AP Stylebook provides in-depth guidance on all aspects of writing principles, even devoting entire chapters to otherwise overlooked topics such as social media. While it can seem cumbersome to adhere to a grammar guideline, any user of AP style quickly realizes that each rule is intended to increase the readability of a written document while also eliminating possible confusion. Additionally, the AP Stylebook is updated each year to reflect common language changes or adhere to new trends.

Admittedly, the “over/more than” debate is a minor one, but the biggest rules remain forever unchanged. Below is a list of the most frequent corrections we in MPC's Public Affairs organization make when proofreading documents. It’s a good idea to keep these in mind next time you’re writing anything – even a grocery list. It’s a great way to impress your friends.


1. Double spacing

Use single spaces between your sentences. Double spacing is a hard habit to break, largely thanks to our teachers in the U.S. who drilled this practice into our muscle memories since our first typing lesson. However, the double-spacing practice really only existed to make it easier for teachers to annotate our papers during proofreading. MPA and APA still allow double spacing, but again, that’s for academic reasons.

Single spacing simply helps your document look cleaner while also adhering to a commonly accepted writing principle.


2. State abbreviations

Unless you’re sending a letter through the postal service, two-letter capital abbreviations are not grammatically correct. If the state is referenced by itself, you never abbreviate it. If it’s accompanied by a city, only states that have six letters or more are abbreviated (exceptions: Hawaii and Alaska, which are always written out). That means a list of our refining locations would look like this: ORD is in Canton, Ohio; LRD is in Garyville, La.; TRD is in Texas City, Texas; MRD is in Detroit, Mich.; and IRD is in Robinson, Ill. Also, take note that the state is always offset by commas.

Incorrect: I was born in Ashland, KY but moved to Findlay, OH when I was in high school.

Correct: I was born in Ashland, Ky., but moved to Findlay, Ohio, when I was in high school.


3. Days, Months and Years

Abbreviating months of the year is another one of those issues where we’re all familiar with many ways to do it, but have never been given guidance on a standard. Like the state names, some of them are abbreviated (the longer-named ones, August through February) and some of them aren’t (March through July). But we abbreviate months only when they accompany a date – they are not abbreviated when the month is stand-alone. Years are always offset by commas unless they follow only a month and no day. Also, never, ever use “th,” “rd,” or “st” after a date. Just stop it.

Incorrect: I think Sept. is my favorite month, so that’s why I can’t wait for August 31st, 2014 to get here.

Correct: I think September is my favorite month, so that’s why I can’t wait for Aug. 31, 2014, to get here.


4. Numbers

I don’t care what your calculator says, numbers under 10 are generally spelled out, while numerals are used for numbers 10 and above. Exceptions: percentages (a 2 percent drop), ages (she’s 4 years old), dimensions/distances (the 9-foot long car drove 3 miles), and monetary units (5 euros).

Trailing zeroes after the decimal are always dropped. The whole idea of “significant digits” only matters in horseshoes and hand grenades. Wait – no, I mean in chemistry and physics. Well, what would only matter in horseshoes and hand grenades? I can’t think of anything that ties those two activities together.

Incorrect: Looking at next year’s forecast for 5 products, profits will be $20.0500 per item.

Correct: Looking at next year’s forecast for five products, profits will be $20.05 per item.


5. Percent and cent

Excluding the percent symbol in a written document started back in the early days of the printing press when the symbol was often hard to read and could be confused with a nine or a six. Ever since, it has been common practice to spell out the word instead of using the symbol. Same goes for the cent symbol.

Incorrect: I think 30% of our savings disappeared thanks to 30¢ transactions every month.

Correct: I think 30 percent of our savings disappeared thanks to 30-cent transactions every month.


6. Hyphens

Did you see the hyphen sneak into the correct example above? The hyphen is there because in that context “30 cent” became a compound modifier. In the simplest terms, hyphens exist to help clarify. As a general rule, the fewer the hyphens the better; you use them only when your sentence would be confusing without them.

Hyphens can link compound modifiers, or words that express a single concept before the noun (except the word “very” or any word ending in -ly). For example, if we were describing a bluish-green dress or bragging about our full-time job, we use hyphens to combine the words into a single adjective. This is also the case for more than two words, as in a “know-it-all attitude.”

If you are the type of person who never uses hyphens and you hear me say that it is a good rule to avoid using them, you might think you’re off the hook. But consider this: the hyphen potentially can avoid some unfortunate misunderstandings. If I wrote, “I’m going to meet with small business employees,” am I meeting with people who work for small businesses, or am I meeting with small people? The hyphen can avoid the confusion. Instead, writing, “I’m going to meet with small-business employees,” helps clarify my meaning.

Incorrect: The wellknown man went to a second rate play with a quick witted woman.

Correct: The well-known man went to a second-rate play with a quick-witted woman.


7. Toward/Towards

It’s the same with forward, backward, upward, and downward: drop the s.


8. Proper nouns

Quick: what’s a noun? Person, place, or thing. Even quicker: what’s a proper noun? The name of a unique, specific person, place, or thing. We all know this, but our definition of what constitutes capitalization has been getting lax. Only proper nouns are capitalized.

Incorrect: Our Leadership Team works to share the importance of adhering to Safety Standards.

Correct: Our leadership team works to share the importance of adhering to safety standards.


9. Titles

Just like proper nouns, titles are another source of confusion. Unless your title includes the company name, it is not a proper noun (and even in that case, only the company name is capitalized). Titles are capitalized if they serve as an adjective before the person’s name, but they aren’t capitalized if they follow the name. Also, no comma is necessary when the title comes before the name, but it is necessary if the title follows.

Incorrect: They gave the document to compliance manager, Jim Smith, at the request of Rick Jones, Student Assistant.

Correct: They gave the document to Compliance Manager Jim Smith at the request of Rick Jones, student assistant.


10. Comma usage

I’m checking my watch right now because I’m not sure I have enough hours in the day to go into every use case for the comma. Traditionally, I think we imagine a comma would exist whenever we take a breath in a sentence. That’s probably pretty good rationale, but it’s far from a standard. After all, using that rule, an in-shape athlete might not use any commas when writing. Well, I suppose there could be several reasons for that.

Anyway, as a high-level overview of the most common comma corrections we make (see what I did there?), know that commas allow you to combine two complete sentences to unify a thought. As a general rule, you’ll only use commas to help clarify a sentence, but use as few as possible. When using a conjunction, if the phrase that follows contains a subject and predicate, you’ll use a comma before the conjunction, not after. If it doesn’t, you’ll leave the comma out.

Incorrect: The cow, laughed quite loudly and, then, he jumped over the moon.

Correct: The cow laughed quite loudly, and then he jumped over the moon.



Those are the top 10 common mistakes we see. Do any of these surprise you? Do you have any examples you’d like to run by us for our input? Let us know in the comments below.


Comments (0)
Thank you for your message. It will be posted after approval.