Oil change

I have a 1996 Toyota corolla with 148000 mi due for smog inspection I have been told to make sure to change the oil before the inspection is this true also car is maintained and runs very good any other ideas? thanks ever one

I don’t know why I would do a special oil change for the smog inspection. If you have been changing oil on a proper scheduled basis and this is not a major oil burner, I would think that you shouldn’t need to do a special oil change.

I would spend my efforts in making sure I had an up to date tune up, within the owner’s manual guidelines.

In addition to the car being “tuned up”, make sure it is well WARMED UP! I failed an inspection once for that reason; the second time around after a brisk highway drive it passed.

If it’s close to your next oil change interval, go ahead and do it before the smog check. The PCV (positive crank ventilation) system of your vehicle is designed to allow your engine to breathe fumes located in oil compartments (oil pan, ect.). The fumes are then burned through the combustion process. If the oil in your engine is contaminated due to inadequate oil changes it may very well cause your vehicle to fail the inspection.

Contaminated oils are high in Hydrocarbons (HC) and will present a rich mixture to the engine chambers. Avoiding oil changes not only causes premature engine wear but can also cause your vehicle to fail the smog inspection. Change the engine oil.


Recognizing that what transman says is absolutely true, I’d be inclined to side with Jayhawk and Doc in that it’d probably pass without the fresh oil if it’s been well maintained and isn’t burning oil, however even if the engine would pass with flying colors if you DON’T change the oil, an extra oil change just to be sure can’t hurt. There is no downside whatsoever to fresh oil.

In short, I agree with Jayhawk but see no reason not to change it anyway.

I’ve never made changing the oil a priority before emissions testing. If the oil change was due I might do it prior to the inspection if I had the time, but if I didn’t have the time to do before I’d do it soon after. If the emissions equipment on the car is in proper operating condition I don’t think an oil change is likely to affect the testing outcome. I never had a car fail due to old oil and I’ve run cars through with 300-400K miles.and using a quart of oil every 1000-1500 miles. The only times I’ve ever failed an emissions test was once because of a bad 02 sensor and once because of a vacuum leak to the MAP sensor I wasn’t aware of.

If its borderline pass/fail, changing the oil can provide you the margin you need…Clean the PCV system, new air filter, take it out and blow the cobs out of it, then have it tested…Good Luck…