Q: I have a 2009 Honda Civic and regularly change its oil when the car's maintenance reminder indicates it's time. I use synthetic oil and was recently told by my oil-change shop that synthetic oil lasts twice as long as conventional oil. Is this true? Considering the maintenance reminder likely does not take into account that the car is running synthetic oil, am I changing my oil twice as often as needed?
A: Honda service literature specifies using a 5W-20 motor oil and changing it at 10,000-mile intervals under "normal" driving or 5,000-mile intervals under "severe service" conditions. Assuming the maintenance reminder indicates it's time to change oil when you're close to the 10,000-mile mark, you are definitely not changing oil too frequently.
In fact, you're braver than I am. I've never been able to wait 10,000 miles or until the oil service reminder indicates it's time for an oil change; I'm just not comfortable waiting that long. Engine sludge buildup occurs as oil is oxidized over time and mileage. Problems from engine sludge still occur, even with today's engine technology and lubricants.
And you are correct: The maintenance monitor doesn't know whether the engine is filled with conventional or synthetic lubricant. Nor does Honda differentiate between the two types of lubricants in terms of oil change intervals.
My personal feeling is that you're actually changing oil roughly half as frequently as you should. I use 5,000 miles as my guide for oil and filter changes. More frequent oil change intervals are cheap insurance for your vehicle. And remember, it absolutely is your vehicle and you, not Honda nor the oil-change shop, are responsible for any repairs it may need.
Q: I own a 2012 Jeep Grand Cherokee with a 5.7-liter Hemi engine. While driving in economy mode, I often hear a clicking noise, which only goes away after I accelerate and vehicle shifts out of economy mode. This noise seems to be getting louder, and other people notice it.
The vehicle runs OK, and checking it with a diagnostic scan tool has produced no trouble codes.
Is it normal for engines with a multiple displacement system, like my Jeep's, to make clicking noises and get louder as they get older, or is this a problem developing?
A: As I described in last week's column, engines that utilize some form of cylinder deactivation to improve fuel economy under cruise or low-load conditions do so by disabling valve operation on specific cylinders. General Motors calls it active fuel management. Chrysler calls it a multiple displacement system, or MDS. On your 5.7-liter V-8, the system selectively disables the first, fourth, sixth and seventh cylinders.
Oil pressure controlled by the MDS solenoids is utilized to deactivate the hydraulic lifters for those cylinders. When the solenoid opens in economy mode, oil pressure is applied to a "lost link" pin that collapses the lifter to prevent it from opening its valve. While the lifter is deactivated, a light spring inside the lifter keeps the lifter base in contact with the camshaft lobe while the upper section of the lifter is stationary. There should be no significant noise from operation when the lifters are deactivated.
My best guess is that one of these lifters is at fault. Perhaps there's a problem with the internal spring failing to keep the base in contact with the camshaft, allowing excess clearance in the valvetrain and creating the clicking sound. Or perhaps the issue is with one of the MDS solenoids.
Also, be aware that all cylinder deactivation systems are very sensitive to oil viscosity, oil pressure and oil cleanliness. Chrysler recommends 5W-20 motor oil changed at 8,000-mile intervals. See my comments above.
Start with a scan of the powertrain control module to see if there are any oil pressure or P3400-series MDS fault codes. Chrysler's scan tool can test the individual solenoids of the MDS system.
ABOUT THE WRITER
Paul Brand, author of "How to Repair Your Car," is an automotive troubleshooter, driving instructor and former race-car driver. Readers may write to him at: Star Tribune, 425 Portland Ave. S., Minneapolis, Minn., 55488 or via email at [email protected]. Please explain the problem in detail and include a daytime phone number. Because of the volume of mail, we cannot provide personal replies.