Dear Dr. Gridlock:

Why is it, during the morning and evening commutes, that 19th and 20th streets NW are full of illegally stopped or parked cars that are neither ticketed nor towed? I travel from Arlington to Dupont Circle every workday, and the gridlock caused by these blockages can be significant, lengthening the trip by as much as 30 minutes.

Illegal parking around George Washington University seems to be the worst in the morning on 20th Street, but in the afternoon, stopped cars from Pennsylvania Avenue to E Street are causing horrendous backups. I have called the university and District police, to no avail.

Francesca Fierro O'Reilly

Arlington

The city really must address these problems to relieve downtown gridlock.

Try lodging a complaint with the mayor's hotline at 202-727-1000. Then try 18th Street NW northbound in the morning and 23rd Street southbound in the evening. Both connect with Constitution Avenue.

Baby on Board, Badly

Dear Dr. Gridlock:

The other day I was in line at a store behind a woman who was carrying an infant in a sling close to her chest.

When I got out to the parking lot, I was appalled to see her backing out of her parking spot with the tiny infant still in the sling, between her and the steering wheel!

James E. Halpin

Alexandria

I would call 911 on that one, then get the license plate and phone child protective services for that area. With all the emphasis on child safety these days, it's astonishing that you would see something like that.

Police Keep Cars Moving

Dear Dr. Gridlock:

Kudos to the Alexandria police for having cops at intersections such as Washington and King streets to keep things moving.

Now, if they could have one at Washington and Duke streets, it would be even better.

Sara Uehlein

Alexandria

A salute to the Alexandria Police Department. Stationing officers at busy intersections is one of the highest-profile assists that the police can offer residents.

Defining Clean Fuel

Dear Dr. Gridlock:

In response to the letter by Chris Magee of Alexandria [Dr. Gridlock, May 19], who saw a Ford Taurus with CF (clean fuel) plates using the HOV lanes: While the Taurus is not a hybrid vehicle, there are hundreds, if not thousands, of Tauruses, Dodge Intrepids and Ford and Dodge full-size vans in our area that were manufactured (not converted) to run on CNG, or compressed natural gas.

I used to work next door to the Natural Gas Association, which maintained a fleet of cars and vans that used CNG and had a refueling station on site. I'm sure those vehicles met the criteria for the CF tags.

What people also need to keep in mind is that it takes more petroleum to make a gallon of premium fuel than it does to make a gallon of regular. If your car requires only regular gas and you are filling it with premium, you are wasting natural resources and contributing to the shortage of oil.

If you want your car to last longer, follow the recommended maintenance spelled out in the owner's manual. Driving in this area qualifies as "severe duty" as defined by most manufacturers, so that means changing the oil and filter every 3,000 miles instead of oil at 7,500 miles and the filter every other change.

David Hirschhorn

Arlington

Thanks for the tips.

Public vs. Private Roads

Dear Dr. Gridlock:

With regard to recent comments on the effectiveness of the Virginia Department of Transportation's public-private partnerships on Route 28, an instructional case for planners is the ongoing upgrading of Interstate 66 and the Dulles Greenway toll road.

I-66 , a state highway, is mired in daily backups along its length from Centreville to Haymarket because the planning for growth (more lanes, more interchanges and the appropriate funding) was not accomplished before the arrival of new homes and residents.

The state bureaucracy is in its usual catch-up mode, with a partial solution of adding four lanes to a three-mile section of the interstate, from Route 234 Business to the Route 234 Bypass.

In contrast, the Greenway's private owner has planned, obtained financing for and begun construction of new lanes, interchanges and toll booths.

The Greenway improvements are being accomplished before the build-out of eastern Loudoun.

Give me that toll and free enterprise every time.

Joe Wagner

Ashburn

If you're suggesting that private enterprise take over more and more of the state's transportation role, that may happen, and it may be a good thing.

But remember, it is county governments such as those in Loudoun, Fairfax and Prince William that are approving runaway development while the state scrambles for dollars to keep up.

Church Traffic Misdirected

Dear Dr. Gridlock:

The practice of businesses and churches being able to hire off-duty police officers to direct traffic in and out of their sites has been discussed previously in your column. Such a situation, on northbound Route 28 near Manassas Regional Airport, has become increasingly irritating.

Each Sunday around noon, three or four uniformed Prince William County sheriff's deputies (whether on duty or off, I don't know) stop traffic on northbound Route 28 to allow vehicles to exit from a large church parking lot.

Given the number of cars in that lot, it is obviously a popular church. But the deputies seem oblivious to the traffic backups they cause, which I have seen stretch for nearly a mile on Route 28.

I am willing to give folks a break, particularly on Sunday morning, but in these situations, don't the officers have some obligation to give priority to the through traffic on the main road?

Michael Ahern

Manassas

In theory. However, if a business or church is paying off-duty officers $25 to $50 an hour to get vehicles into and out of parking lots, it's only human nature that those officers would give priority to the concern that is paying them.

That is why I oppose entities -- including churches -- renting cops. Police should serve all of the public all the time, and not some of the public sometimes.

Seeking Driver Training

Dear Dr. Gridlock:

From time to time, you have provided information on defensive driving courses for teens. I have been searching the Web without much luck in finding the one I sent two grandchildren to in the past. They were particularly good, with hands-on training and solid tips that have helped both my grandkids in tough situations during the past few years.

I would like to refer others to the group but have given away all the literature I received online, and I changed computers without keeping the Web site in my favorites file.

I would greatly appreciate a list of the best ones you have listed in the past, as I am certain I will recognize the organization and be able to go to its Web site for information.

Walter Ochs

Annandale

I have mentioned three companies:

(1) Car Guys Inc., of Rockville, 800-800-GUYS.

(2) BSR Inc., of Summit Point, W.Va., 304-725-6512.

(3) Driver's Edge, of Las Vegas, which has touring clinics that come to this area, 702-896-6482.

I've received positive feedback on all of them.

Who Can Use HOV?

Dear Dr. Gridlock:

Darrel Smith of Montclair complained about law enforcement vehicles using HOV lanes [Dr. Gridlock, May 19]. He spoke of those cars being used for personal reasons. I'd like to know how Mr. Smith could ever know whether those drivers are using government cars for personal use.

Certainly he's not guessing based on how the occupant is dressed? Law enforcement officers use all kind of vehicles and all kinds of license plates, some of which are not recognizable as being for law enforcement. That is for obvious reasons.

The vast majority of law enforcement personnel work on call, and the need for a quick response could arise at any moment. Kind of hard to do when sitting in backed-up traffic in the regular lanes.

It's hard enough to respond quickly anytime in the Washington area, but the use of HOV lanes may speed up the response.

If government (non-law enforcement) employees are pulled over when using a government-issued car, then they deserve to be cited. But lay off exempt drivers.

Wayne Stewart

Manassas

Many readers have said that government vehicles with a single occupant are a significant cause of congestion in the HOV lanes.

Darrel Smith contended that law enforcement commuters should not be exempt from HOV restrictions just to travel to work. You suggest otherwise. The point seems moot because law enforcement personnel are exempt from HOV restrictions whether they are on or off duty.

What seems to be a problem to some is the number of government vehicles (not law enforcement) whose drivers are not exempt and seem to be taking advantage of HOV rules.

When to Change Oil

Dear Dr. Gridlock:

You recently published tips from readers about how to keep their cars running longer. One was to change the oil frequently.

Several years ago, Consumer Reports published an article describing how the magazine had intended to rate motor oils. What the magazine discovered was that all oils that met certain standards appeared to perform equally.

Despite meticulous tests conducted on New York City taxicabs with specially rebuilt engines and carefully calibrated pistons, the testers could not document any wear after 10,000 miles.

So they instead tested for the optimum frequency of vehicle oil changes. After running up another 10,000 miles or so, they simply gave up and advised motorists to change the oil per the manufacturer's recommendations.

From the ConsumerReports.org Web site today:

"Myth: Engine oil should be changed every 3,000 miles.

"Reality: Although oil companies and quick-lube shops like to promote this idea, it's usually not necessary. Go by the recommended oil change schedule in your vehicle's owner's manual. Most vehicles driven under normal conditions can go 7,500 miles or more between oil changes.

Some models now come with a monitoring system that alerts the driver when the oil needs changing. Depending on driving conditions, these can extend change intervals to 10,000 or 15,000 miles."

Jay Anania

Chevy Chase

All that may be true. However, of the dozens of readers who explained to me how they kept their vehicles running for hundreds of thousands of miles, the number one reason given was oil changes every 3,000 to 6,000 miles.

Transportation researcher Diane Mattingly contributed to this column.

You can write to Dr. Gridlock at 1150 15th St. NW, Washington, D.C. 20071. He prefers e-mails at drgridlock@washpost.com or faxes at 703-352-3908. Include your full name, town, county and day and evening telephone numbers. Dr. Gridlock cannot take phone calls.