Dayton Daily News

Wheels: An e-mail from Romey says, "What are your thoughts on continuously variable transmissions (CVT). Our newspaper, the Dayton Daily News, recently had a listing of the "8 Low-Cost Vehicle Options for 2009." The Smart car was the only one listed with a CVT transmission. All the other cars had manual transmissions listed.

"What are your thoughts on CVT transmissions relative to initial cost, fuel economy, durability (will they last 200,000 miles), distinct advantages to the CVT, and are there different types? Do you think this is the wave of the future?"

Halderman: Thanks for writing with a good question. Without a doubt, a CVT transmission offers better fuel economy than a conventional automatic transmission and this is one of the reasons that it is being used by more vehicle manufacturers. It has some advantages and disadvantages just as any transmission design.

Advantages:

1. Very smooth without any jerking because it doesn't actually shift gears like a conventional automatic transmission.

2. Allows the vehicle to achieve fuel economy close to that of a manual transmission.

Disadvantages:

1. Unknown long-term durability. The Ford 500 did offer a CVT, but it was dropped and replaced with a 6-speed automatic. I read that the warranty cost was about double that of the 6-speed.

2. Cannot be repaired and instead is now a replacement-only assembly, which could be costly.

What do I think about a CVT? I do like the smoothness. I do not like the high engine speed when climbing hills. I prefer a conventional automatic transmission, especially if it is a

6- or more- speed automatic.

Wheels: A reader writes, "I have a 2005 Lexus RX 330 and while driving, the "VCS" (vehicle stability control system), the "BRAKE" and "ABS" (antilock braking system) lights come on simultaneously. Then, after driving for an hour, the lights disappear if I turn off the engine and restart the car. This happens every time I drive the car. I had a parts store check for trouble codes and they did not find any stored codes. A friend said it could be a bad oxygen sensor. What could cause this problem?"

Halderman: If the brake fluid level is just slightly low, it can cause these warning lights to come on. When cold, the brake fluid shrinks and the levels drop. Then, when it warms a little, the level will be okay and not show a fault. Add some DOT 3 brake fluid from a new container and the warning lights should stay off. Do not add above the "MAX" level to allow room for expansion.

The "Check Engine" light (symbol of an engine) would come on if the computer sensed a problem with the oxygen sensor or other engine-related faults and there would also be a diagnostic trouble code (DTC) stored, so the parts store would have found that during their inspection.

They may not have noticed if the brake fluid is slightly down. In my experience, the warning light will come on long before the brake fluid level reaches the low mark.

As brake pads wear normally, the caliper piston has to move out of the bore to compensate. This means that the brake fluid level will drop.

James D. Halderman is an ASE-certified master technician and the author of 12 textbooks. E-mail him at jhalderman2@juno.com.