In most states, a car needs to pass a smog test, also known as an emissions test, before you can register it and drive in on public streets. If your car is on the older side and no longer runs as efficiently as it once did, then getting it to pass this smog test can be a bit of a challenge. Here are a few things you can do in the weeks leading up to your smog test in order to increase the chances of your car passing.
Change the oil
A car that has dirty oil will give off more emissions than one that's running with new, clean oil. So, arrange to have an oil change a week or two before your smog test is due. Replace the oil with full synthetic oil, since this tends to give off fewer emissions than standard oil. Make sure your mechanic also changes the oil filter when they change your oil. In most auto shops, the filter is automatically changed with the oil -- just check to ensure this is the policy where you take your car.
Drive at high speeds
In the week before your smog test, take your car out for a few drives on the highway, and make sure you spend an hour or two cruising along at highway speeds -- 65 miles per hour or more. This will help burn off any oil and gas residues in your engine. The hope is that these residues will burn off while you're out on the highway rather than during the smog test.
Properly inflate your tires
Check the inside rims of your tires to see what the recommended inflation level is. Then, inflate your tires to this pressure. When your tires are inflated to the proper pressure, your engine won't have to work as hard -- so it probably won't give off as many pollutants. If you think your tires may have a slow leak, make sure you inflate them just before you drive to the mechanic's shop for your smog test.
Use a gas cleaner
There might be some residue in your gas tank. If it runs through the engine during your smog test, it may result in less-than-satisfactory results. So, a few weeks before your test, put a gas cleaner in your tank, and then drive the car until the gas tank is empty. Fill the tank again, and you're ready for your test.
For more information on cars and smog tests, visit: http://www.westcoastsmogtest.com