Q: About two years ago, I purchased a used 2007 Scion tC for my daughter. It had about 95,000 miles on it at the time. Current mileage is 125,000 and the car drives very well.

However, the tC has a known engine oil consumption issue.

I had a consumption test performed last year, which revealed that after 1,200 miles, the car consumed about three-quarters of a quart of oil. These numbers, I was told, meant the car didn’t need repair. The dealer said I need to prove the car consumes a full quart of oil over 1,200 miles to qualify for free repairs.

So, I have two questions: First, what exactly is the dealer going to repair? Second, when would I know if a new clutch is needed? Are there any warning signs?

A: As they age, some of the Toyota engines used in Scions (Toyota recently killed the brand) suffer from increased oil consumption. A revised piston, along with new piston rings, is the recommended repair when deemed necessary. If cylinder bore crosshatching is no longer visible, or vertical bore scoring is evident, replacement of the entire short block is advised. This is an approximately 15-hour repair that involves engine removal and significant engine disassembly, reassembly and reinstallation.

Toyota isn’t the only carmaker to run into oil consumption problems, which in part may be caused by the use of low-tension piston rings and a friction-reducing, fuel-economy-enhancing design.

If it were my car, I’d rather add a quart of oil every thousand miles than have my beautifully running robot-built engine removed, disassembled, reassembled and reinstalled by a less-than-perfect human.

Signs of a worn or faulty clutch include chattering upon engagement, difficulty shifting into gear at a stop, gear clashing and engagement that occurs high on the pedal.

Q: I was looking at a friend’s four-cylinder Honda Accord engine and was surprised to see the catalytic converter was bolted directly to the cylinder head. What’s up with this? Where are the headers?

A: This is a strategy to help the catalytic converter reach operating temperature as quickly as possible after a cold engine start. The cylinder head is designed in such a way it incorporates the passages formerly found in an exhaust manifold.

Modern vehicles emit almost no emissions once the engine and catalytic converter are at operating temperature. Minimizing emissions after a cold start is still a work in process. Thanks to great engineering and materials usage, modern vehicles enter closed loop within seconds instead of minutes. This means the air-fuel mixture is no longer enriched, and the air-fuel sensor signal is ready to go, and listened to, so a stoichiometric mixture (the perfect mixture for complete combustion and catalytic converter function) can be maintained.