> wrote
> Hello. I own a 2003 Accord 4-cyl and wondering what, if any
> difference, having mostly highway mileage on my car does to the
> frequency needed for my oil change? The manual recommends every 5,000
> miles/6 months.

Can you double check this? My 91 Civic has an interval of 7500 miles/6
months, for non-severe driving (see below).

> Does the fact that at least 75% of my mileage comes
> from non-stop interstate highway travel at speeds of 70 mph help or
> hurt me in terms of oil change frequency?

I would wager it should help you.

My Honda owner's manual includes, under "severe driving conditions" that
warrant more frequent oil changes, "repeated short distance driving." For
such driving (along with dusty and/or cold conditions?), the manual
recommends changing every 3000 miles or 3 months. Does your manual say
anything like this?

Consumer Reports did an interesting, albeit arguably amateurish, study of
motor oils in New York City taxicabs in 1996. Some folks here loathe
consumer reports and criticize the study; yet what they recommend is
generally the same as what CR ended up recommending!

See the article at http://www.xs11.com/stories/croil96.htm .

Excerpts:
-------
The long-time mantra of auto mechanics has been to change your oil every
3000 miles. Most automakers recommend an oil change every 7,500 miles (and a
specific time interval) for "normal" driving, and every 3,000 miles for
"severe" driving - frequent trips of less than four or five miles,
stop-and-go traffic, extended idling, towing a trailer, or dusty or
extremely cold conditions. Many motorists' driving falls into one or more of
those "severe" categories.
....
The bottom line. Modern motor oils needn't be changed as often as oils did
years ago. More frequent oil changes won't hurt your car, but you could be
spending money unnecessarily and adding to the nation's energy and
oil-disposal problems.

Even in the severe driving conditions that a New York City taxi endures, we
noted no benefit from changing the oil every 3,000 miles rather than every
6,000. If your driving falls into the "normal" service category, changing
the oil every 7,500 miles (or at the automaker's suggested intervals) should
certainly provide adequate protection. (We recommend changing the oil filter
with each oil change.)
----------

> Of course, with the long
> commute every day, I get to 5,000 miles before 6 months, and thus not
> only do I spend a ton in gas, but it seems I have to get my oil changed
> every 4 months or so, which costs more money. Any thoughts and input
> are appreciated. Thanks in advance.

Keep reading the posts to this thread. The only comment I reject outright at
the moment is the one that says change the oil every 3000 miles.