For several years, I’ve been urging readers to avoid adjustable-rate mortgages and opt instead for fixed-rate loans with 15- or 30-year terms.

But I’ve felt a little guilty about it, since I’ve never seen fit to replace my own adjustable mortgage. In fact, my ARM, taken out when conditions were unusually favorable, has saved me a tidy sum during the past 10 years.

Given the persistent sluggishness of the economy and the chance that interest rates will stay low for some time, anyone buying a home or thinking of refinancing should consider whether an ARM makes sense, since deals have gotten better recently.

With a little hunting, you can find a new ARM with a starting rate of about 4 percent, about 2 percentage points less than the average 30-year fixed loan. For every $1,000 borrowed, the monthly payment on a 4 percent ARM would be $4.77, versus $6 on the 6 percent fixed loan. On a $200,000 loan you would pay $954 a month rather than $1,200. With a lower rate, you could qualify for a bigger loan.

As the name implies, an adjustable-rate mortgage adjusts. Every 12 months, a new monthly payment is calculated by applying a new interest rate to the remaining debt and the number of years left on the original term of the loan.

In most cases, the interest rate is figured by adding 2.75 percentage points to the current rate paid by one-year Treasury bills. With those yielding about 1.3 percent, an ARM adjusting today might charge only 4.05 percent for the next 12 months.

I say “might” because there’s a catch. Most ARMs have a “cap” limiting annual changes to no more than two percentage points above or below the previous rate. In addition, they have a lifetime cap that keeps the rate from ever going more than 6 points above or below where it started.

Obviously, ARMs are something of a crap shoot, since future rates can go up as well as down. There’s been little reason during the past few years to take the ARM gamble when a fixed-rate deal offered the chance to lock in a low rate for the life of the loan.

An ARM is not attractive unless its starting “teaser” rate is substantially lower than the fixed-loan rate. And that is what has happened recently — the gap has widened to nearly 2 percentage points. It’s not as wide as it was when I got my ARM in 1993, but it’s wider than it’s been for the past few years.

In addition, the low starting rate means a newly issued ARM would never adjust to a rate above about 10 percent. A year ago, new ARMs were charging 5.4 percent, meaning they could eventually go as high as 11.4 percent.

Of course, if prevailing rates were to jump, an ARM issued today could adjust to as high as 6 percent in a year — the same as you’d get with a new fixed loan today. But you’d have saved 2 points the first year by having an ARM, and then you’d pay the same the second year as the fixed loan would charge. At the start of the third year, your ARM could go as high as 8 percent, 2 points above the fixed loan. Then it would start wiping out the savings you’d enjoyed in the first year.

In other words, if ARM rates rose the maximum allowed, you’d have three years before the total ARM cost exceeded that of the fixed loan.

There are, then, three factors that could make an ARM appealing:

• You need the lower payment to qualify for a bigger loan.
• You think short-term interest rates will stay low, keeping your ARM rate low.
• You don’t expect to have the mortgage for very long, so the risk of higher rates in the future isn’t important.

My 10-year-old ARM started at below 4 percent, about 2.5 percentage points less than a fixed loan at the time. With the lower payments, I used the money I saved every month to make extra principal payments on the mortgage. Since the remaining debt was smaller each time the new payment was figured, the required payment gradually got lower.

I keep making larger-than-required payments to free myself of the mortgage early — reducing worry about rates going higher in the future.