Mystery oil consumption - 2002 Highlander V6

I have a 2002 Toyota Highlander V6 with 130,000 miles which had exhibited negligible oil consumption between oil changes -- that is, until about a
month ago.
Just as I was arriving home from work, I saw the low oil pressure light blip on for a moment. When I checked the oil level, I found almost nothing was showing on the dipstick!
I refilled it to the full line and have been monitoring it every few days, checking it first thing in the morning before starting to make it easy to see the oil on the dipstick.
It is using about 1 quart of oil (Mobil 1 synthetic - I've used synthetic oil since the 10,000 mile mark) every 5,000 miles now after using nothing during the first 120,000 miles. There are no visible leaks, and I don't see anything unusual with the exhaust to show oil consumption.
Any idea where the 1 quart of oil every 5,000 miles is going?
Bud H
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Bud, Strange problem. I couldnt imagine what has gone on in your Highlander. I use Mobil 1 also and have no oil consumption . Please keep us posted on what you find out. Scott
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Full synthetic oil IS NOT recommended for high mileage engines such as yours as the synthetic formulation has a tendancy to seep through seals & gaskets more than conventional motor oils. I have seen NUMEROUS vehicles with 75,000 plus miles exibit "mysterious" oil consumption or annoying leaks while using synthetic oils, just to have the problem solved by switching back to conventional motor oil and having it changed as recommended.
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MrFixit469 wrote:

Lots of big trucks run their engines over a million miles on synthetic oil, Mobil Delvac 1 being one of the oils. There sometimes is a problem starting synthetic oil on high mileage engines, but that goes away after one to three oil change intervals.
I do not know where the Highlander oil might be going.
Ken
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check pcv valve and filter..
http://www.minibite.com/america/malone.htm
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actually ken, if you switch to synthetic oil after you have been using conventional oil for some time the problem should not go away. in conventional oil the oil molecules are larger than those in synthetic oil. that is why people who switch to synthetic oil after long use of convetional oil are complaing of oil consumption and oil leaks.
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