Is oil filtration system worth it? A resounding no

Q: I have a Dodge with a high output Cummins diesel engine that I want to keep for many, many years. Currently it has 71,000 miles. I use synthetic oil in it but changing the oil every 5,000 miles is getting expensive. I am thinking about installing an oil filtration system that takes 10 percent of the oil from the oil pan and filters particles of less than 5 microns. The cost of this device is more than the cost of a year of oil changes. What do you think of this filtration system?

M.B., e-mail A: Using synthetic lubricant is great. However, even if the system filtered 100 percent of the oil of all particles less than 5 microns and greater, I still advise changing the oil and oil filter at a 5,000 mile interval or less. The only way to protect the engine from wear is to dump the old oil, replace the oil filter and pour in a fresh supply of lubricant, and even this does not remove all the contaminates from an engine.

Q: I believe tires should last 40,000 miles with proper care. Recently my mother was told the tires on her 1998 Mercedes-Benz C230 needed replacing because one was excessively worn in the center and another had bumps. The tires only have 20,000 miles on them. This is the second set of tires. The first set of tires lasted 40,000 miles. Mom is not an aggressive driver and the car dealer shop takes care of the tire pressure. Why did the tires wear so rapidly?

C.W., e-mail A: It is time for mom to take over the job of checking the tire inflation pressure. It is apparent shop personnel are not doing a proper job. The one tire with excessive wear in the center possibly suffered from over-inflation. It is also possible tire wear such as described was the result of being stuck in snow. The bumpy tire may be the result of improper balance. Your mom doe not have much control over this, but if she felt a vibration in the car, she might consider a trip to a repair shop to have the balance problem cured.

If she is not going to check the tire inflation pressure every month herself, she should consider taking the car to a shop within a mile of her residence. For proper inflation, the tires need to be cold. The best time to check inflation is in the morning after the car has been parked overnight. All the details about how to check inflation pressure is in her owner's guide.

Q: A few months ago the air bag light illuminated in my 2001 Ford Ranger. Since then it turns on and off on a regular basis although not every time. Has Ford issued any technical service bulletins about this? What do you think is wrong?

G.E., e-mail A: Ford has issued a technical service bulletin that might affect your vehicle. On some Ford Rangers the wiring connections for the safety belt pretensioner system might become corroded.

After a technician follows all safety procedures so the air bags do not deploy, he should check for diagnostic trouble codes. He also may check the connections for corrosion. If the connections are the cause of the trouble, he cleans them with factory recommended electrical cleaners and the trouble is repaired. This could be the trouble.

Phil Arendt is a columnist, consultant and A.S.E.-certified master technician. Readers may send questions to Dr. Gizmo at P.O. Box 548, Cary, Ill., 60013, or his e-mail box drgizmo@drgizmo.ws. Dr. Gizmo