Q I have a 2004 Honda Odyssey with 90,000 miles with a small amount of oil seepage under the transmission and engine. The dealer recommends a costly repair but is not too concerned about it. I have heard of a "magic" caulk that can be applied over any surface to seal a minor leak. Is this true?

A I wouldn't worry until the "seepage" becomes a "leak" that forces you to check the oil level every couple of days. The oil is likely coming from the engine's rear main seal which, as the dealer advised, is a costly repair and in most cases is not physically accessible without major disassembly.

Over the years, I've tried virtually every type of "stop-leak" product for oil leaks -- with virtually no success. Most of the products are intended to be added to the oil and contain ethers that tend to swell seals, hopefully stopping or slowing the leak. Ethers also tend to thin the motor oil, which I've never been a fan of. So, just make sure to keep the oil level up and don't worry too much unless it becomes a significant leak.

Q A mechanic pointed out that the rear drum brakes on my RWD 2000 Mitsubishi Montero were not functioning properly and needed adjusting. I had always understood that rear brake shoes are automatically adjusted each time the brakes are applied while driving in reverse. But I was told that applying the hand brake also serves to adjust the rear brakes. Is this true?

A Your RWD Montero features rear drum brakes that require the application of the parking brake to adjust the rear brake shoes. When clearance between shoe and drum reaches a certain amount, applying the parking brake moves the shoes enough to ratchet the adjuster mechanism, moving the shoes closer to the drum in the at-rest position. So, in order to keep the rear drum brakes properly adjusted, you'll need to use the parking brake regularly, or manually adjust the brakes as your mechanic did.

On many vehicles, rear drum brakes utilize a self-adjusting mechanism that is activated by applying the foot-operated brakes while backing up. The self-actuating design pulls the shoes against the inside of the drum when applied in reverse. When the gap between the shoe and drum is large enough, the movement of the shoe rotates the self-adjuster enough to "click" or ratchet a notch, moving the shoe closer to the drum in the at-rest position.

Q I had my 1999 Lincoln Town Car in for a 90,000-mile servicing and was told the car needed a new serpentine belt. It was replaced along with the tensioner. The gas mileage according to the car's computer readout was about 16 miles per gallon before the belt replacement but abruptly fell to about 13 mpg. The dealer told me they did nothing to cause this sudden drop in mileage. Before returning to the dealer I'd appreciate your opinion.

A According to my Alldata automotive database, the maintenance schedule for your vehicle calls for no service to the serpentine belt until an inspection at 100,000 miles. That's about the typical life expectancy for this type of belt, so replacing it at this mileage is not unusual.

More importantly, replacing the serpentine belt should have no impact on performance or fuel mileage. This is the accessory drive belt, which drives the alternator, power steering pump, air-conditioning compressor and water pump. I'd ask the dealer to double-check its workmanship to make sure something like an electrical harness connector was not left unplugged. An issue with the coolant sensor, mass airflow sensor or something similar would certainly affect fuel mileage.