Oil change interval exceeds time recommendation not mileage - now what?

oil
xb
scion

#1

i just bought a used 2006 scion xB (owned in Phoenix by a nice old lady since new) with only 14k miles in immaculate condition. I thought I had a gem, but I discovered the oil change history exceeds manufacturer time recommendation of every 6 months: changes occurred at 7 months, 17 months, 8 months, 15 months, and 11 months. Mileage recommendation is every 5000 miles; oil was changed after 2000, then 4500, 1500, 2800, and 3600. i read that oil oxidizes over time and if left in the engine for longer than recommended and used on short trips causes internal engine deposits, corrosion and sludge? If I now change the oil more frequently than recommended will it remove any such bad stuff? Should I be worried? Thank you. Doug


#2

Don’t worry. None of the past change intervals was long enough to cause a problem. You still have a gem.

Follow the oil change recommendations in the manual from now on and enjoy your xB.

Granted, 17 months is a long time, but the engine is young, and it will survive. I seriously doubt there’s been any long-term damage.

The horror stories you’ve been reading are over-hyped, and probably meant to sell you something. Something you don’t need.

I have a car that sometimes doesn’t get driven much, and when this happens I change its oil once a year. I’ve owned this car for more than ten years and it continues to run perfectly.


#3

In your case you should be fine. Motor oil oxidizes very slowly. The time recommendation is largely irrelevant today as additives have stabilized the oil so much that 5000 + miles really is a good number. Time is not a huge issue at this point. 17 months was a bit long but not enough to be an issue. Oxidation is now more an issue for cars that idle long periods of time, but they are on a severe service schedule which this car probably does not meet.


#4

It appears that it was changed often enough that (hopefully) any sludge issues will not be much of a concern.
The fact the car is from a dry climate area instead of a humid one is also a plus.

If there is any concern about sludging this could be verified by removing the valve cover and inspecting the valve train. One could also run a heavy wire (piece of coat hanger, brazing rod, etc.) probe inside the oil pan and scrape the bottom a bit during the next oil change. If the wire comes out with a trace I would not be alarmed over that. If it comes out with a gob of goo on it then maybe.


#5

I would not orry at all about this. If this had gone on for 100k miles, then maybe, but not for 14k.