Dear Tom,
I’d like to know how often I have to change the oil in my Chevy Trailblazer with 58,000 miles?
Butch from NV
Butch,
Your truck is equipped with an oil life monitor. This system measures when to change the oil based on three criteria: crankcase temperature, combustion chamber events (work the engine does), and moisture in the system. The system is accurate to within (+) or (– ) 5 percent of oil life. Just make sure the system is reset every time you change the oil and always use the oil that GM recommends or a better oil. Follow the dictates of the OLM and you will not go wrong. Success to you.
Tom
Dear Tom,
I own a 2000 Grand Prix that lurches when I shift. No codes were detected in the system. Any idea what could cause this lurching?
Bruce from Appleton, NY
Bruce,
Your Grand Prix should have a 4T65E transaxle. You car’s computer controls the line pressure in this transmission, which affects shift firmness/softness. If the transmission is worn out and slipping, the computer compensates by raising the trans line pressure, causing a harsher shift. Test drive the vehicle with a scan tool attached to the in-vehicle data link connector to monitor transmission data. This will give you more info on what could be causing the problem. It may store a P1811 code in the future. Other causes of harsh shifts are stuck valve in the valve body, plugged trans oil filter, bad TPS (Throttle Position Sensor), high engine idle, large vacuum leak, and a host of other stuff that needs to be checked out. Success to you.
Tom
Dear Tom,
I own an ’03 Olds Alero. The AC stopped cooling, and the compressor is not turning when the switch is on. It turns free by hand when the engine is off. I checked the fuses and they are good. Could it be a relay? If so, where are they located? Thanks for your help.
Gerald from Mountain City, TN
Gerald,
If the refrigerant charge is low in the system, then the computer will not allow the compressor to engage because it detects low refrigerant pressure. This is a built-in fail-safe to protect the compressor from running with no refrigerant oil. A garage will need to check the refrigerant level. If the level is low, they will locate the leak, repair it, and recharge the system with refrigerant and oil. If the refrigerant level is OK, then system pressure switches and powers and grounds from the computer will need to be checked for faults. Best to you.
Tom
Tom Torbjornsen is an automotive expert of 37 years. An automotive journalist in good standing with the IMPA (International Motor Press Association) and MPG (Motor Press Guild), Torbjornsen is the Repair and Maintenance Editor for AOL Autos, At Home Portals and many other websites. Hear his radio show. America’s Car Show, on the SSI Radio Network Saturdays at 8 a.m. Listen to the show on the live stream during regular show times at www.americascarshow.com. Send your car questions to his website at www.americascarshow.com. You can also find Tom’s book, “How To Make Your Car Last Forever,” in local Barnes & Nobel booksellers, or order online at Amazon.com.
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