So a family member has a 2002 Toyota Camry, 4 cylinder, that has been maintained by the book. It currently has an erratic oil consumption problem. You can take a 250 mile road trip and be fine, then turn around and take another and consume between 0.5 and 1 quart of oil. They hadn’t changed the PCV valve (Toyota didn’t recommend it in their manual), so they did that at my reco as a first easy cheap step to no avail. On startup after a few hours/overnight rest, it will put out a puff of blue-gray smoke that clears after a few seconds of running - that has me thinking valve stem seals, which seem to be a consistent issue with 4 cylinder Camrys for going on 20+ years… but I’ve never seen that lead to erratic high oil consumption, just a steady, low amount.
The first thing to do is pull the valve cover to see if any of the oil drain-back holes are plugged.
Sludge can form around the drain-back holes where the oil doesn’t return back to the oil pan after the engine is turned off. This oil stays on the head and leaks past the valve guide seals and the engine smokes on start-up.
And if the oil has pooled in the head and not returning to the oil pan, it can result in an inaccurate oil level reading.
@tester - good thoughts - I hadn’t considered it, since the car has had regular oil changes every 3k (has 140k on it now), and I’ve never seen a car with 3k oil change intervals sludge. I don’t quite follow how this could lead to erratic oil consumption, though, where it can go a few weeks without any loss and then suddenly lose considerable amounts of oil over a short time. I would expect the oil reading to be erratic all the time…
I think Tester’s suggestion is a good one, but I also think your original thoughts of valve stem seals is also a good thought. In both cases, how much oil will be burned is highly dependant upon how the vehicle is driven. Lots of driving using the gears to keep the car from speedin up, lots of downshifting to slow, these things cause high vacuum in the cylinders, and if you’re pulling oil in that’s when it’ll happen. And you already know you have a problem with the valve stem seals.
Looking at the plugs could yield a valuable clue too. ’
And I definitely think a compression test is in order. Wet & dry.