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2005 Toyota Highlander - Suddenly needs oil

Over the last 3 months my 2005 2.4l engine Toyota Highlander has needed 3 quarts of oil, which has never happened before. It has 164,000 miles. Any idea why this might have started now? I always changed standard oil every 3 to 5,000 miles and just switched to full synthetic oil about a year ago. Please help if you have suggestions.

How many miles did you drive in that 3 months? Just saying 3 quarts in 3 month doesn’t tell us anything. If you drove 6000 miles in 3 months, that is 2000 miles a quart. Nothing wrong. If you drove 3000 miles, that is 1000 miles a quart. Still within acceptable range.

So which is it?


You problem might have to do with the vehicle being nearly 15 years old with 164K miles on the engine.

I also wonder if your engine just doesn’t “like” synthetic oil. Perhaps try switching back to regular and see if the problem goes away or changes.


I would replace the pcv valve if it has one , a bad one can cause increased oil consumption . A cheap fix first .


I drove 4,000 miles the last 3 mths or 1,250 / qt of oil. So your saying this is acceptable??

14 year old vehicle that now has synthetic oil in it and was probably not specified in the first place . You wrote 1,250 but I guess you mean 1 and 1/4 quarts of oil. Go back to what the manual says to use and it might not use that much again. But even at that just keep the level at full and drive on.

Yes, the consumption of 1 qt of oil in 1,250 miles–in a 14 year old engine with more than 164k miles on the odometer–is acceptable.
How would you feel if you were the owner of a brand-new Mercedes or BMW, both of whose manufacturers state that the consumption of 1 qt of oil every 600 miles is “normal”.

On a 147k engine, yes.

I would switch back to conventional oil to see if consumption drops back to levels more acceptable to you. A friend started putting synthetic in his high mile Toyota and found high oil consumption. He switched back to conventional and it improved.

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My friend’s Rav-4, which has an oil consumption problem, definitely consumes less oil with conventional Pennzoil, as compared to (synthetic) Mobil-1, or several other conventional oils.


I’d use whatever Toyota recommended in the owner’s manual. Given the age, it’s probably mineral oil and not synthetic. Mineral oil got you this far, it’ll be fine as long as you continue monitoring and changing on a regular and reasonable schedule.

Ill be going back to convert oil soon.n

I’ll change it (PCV Value) out next week. Thanks.

Good suggestion. I’ll try that next week.

Yeah I think there is no reason to go synthetic and just go back and see what happens. I understand 160K is a lot of miles but still my Riviera had 500K and never used a quart between 3000 mile oil changes. Yeah and my son’s new BMW did go through a quart in his first 800 mile drive, so you never know. But your history suggests regular oil might put you back to where you were.

Good suggestion. I’ll do that for the next oil change.