Doug McAllister: Under the hood Cars need oil change after length sit

Q. I read the column you published last month about oil life and had a related question. I store a 2002 Corvette six months out of the year. It gets limited use during the other 6 months. It went into storage with a fresh change of synthetic oil. If I only drive the car 1,000 miles a year, what would be the recommended oil change interval?

A. Your situation is a little unique and I am not sure there is a perfect answer. If it were mine I would probably change the oil when I pulled it out of storage every year. Since you are using a full synthetic motor oil, it probably would not hurt anything if you changed it every other year; I just don’t like the idea of leaving the oil in that long, and I would feel a lot better knowing I have fresh oil to start the season. Enjoy your Corvette this summer, now that it’s finally here.

Q. My 1994 Honda Accord LX has stalled out twice — once at a stop sign. The car restarted after six or seven attempts. The weather was dry. I took it to my reliable repair shop and they could not find anything wrong. The next time it happened two weeks later, I was driving 50 to 55 miles per hour in a snowstorm, on the Interstate. Suddenly I had no power. I coasted to the shoulder and called 911 for help.

While waiting for help I got the car restarted after six or seven attempts. I decided to accept the tow to a very reliable repair shop in Portage, Wis. They could not find anything wrong. I was told the problem cannot be duplicated in a car repair shop. Is this an electrical problem? The mileage on my car is 139,820.

A. As you know it is very hard to diagnose a problem like this without having it fail when you are testing the car. However, when I read your description of the problem, the first thing that came to my mind is: your car has a bad distributor.

We saw a lot of problems with distributors on this model Honda and they would act just like you described. If everything else tests out OK, I would take a chance on a distributor replacement. We did see some relay failures on those cars, as well, but the distributor was very common.

Q. I had an interesting problem come up on my 2008 Chevrolet Silverado 1500 four-wheel drive with the 5.3 engine and Active Fuel Management (AFM) system. I was having a couple of issues. The first was a very slight vibration that I felt mostly through the gas pedal when cruising at certain speeds, typically 45 to 55 mph. I figured this was the engine switching from eight cylinders down to four to save on fuel, but I wasn’t sure about that and it was slightly annoying.

The other issue was a fairly loud clanking noise that sometimes happened when I first started up in the morning and shifted into reverse. It didn’t do it every time and only did this when the car was cold, and so it didn’t do it again for the rest of the day — it had to sit overnight.

The Chevrolet mechanic checked the universal joints and they were OK — no problem with them and he thought the slight vibration was probably the AFM switching to four cylinders. Since I was not satisfied with that answer, I left the truck overnight so they could see it in the morning and it turns out they had to replace the drive shaft. It looked fine on a visual inspection but after swapping it with another truck all the problems went away. They sent the drive shaft in for analysis. What are your thoughts on this?

A. I’m glad they got to the bottom of it for you. Vibrations can be annoying and really hard to track down sometimes. From your description it really sounds to me like there was a bad u-joint on the drive shaft that just was not visible on inspection. I have seen that before where there is just the slightest play in one of them, or it is off center just a tiny bit, causing clunking and or vibration problems. It would be interesting to see what the analysis found but my guess is we will never know. The bottom line is your truck is fixed and hopefully under warranty!

Ÿ Douglas Automotive is at 312 S. Hager Ave., Barrington, (847) 381-0454, and 7218B Virginia Road, Crystal Lake, (815) 356-0440. For information, visit douglasautomotive.com. Send questions to underthehood@dailyherald.com.