Expedia Engines Guide · Symptom guide
The disappearing quart: measure it right before you worry about it
The light came on between oil changes. You added a quart. Then another. Now you are doing math in your head at the parts-store counter and wondering if the engine is done. Stop doing that math, because the first number is almost certainly wrong.
Measure it right, once
Dipsticks lie when the conditions change. Park in the same spot, engine cold, car level. Pull the stick, wipe it, seat it fully, pull it again. Write the level down with the mileage. Do the same thing every fill-up for a month. Same spot, same temperature, same procedure. What you had before this was vibes. What you have now is a consumption rate, and a consumption rate is a fact you can act on.
The other measurement mistake: trusting the dashboard. Some cars trigger the low-oil warning when they are a quart and a half down. A quart and a half down at 4,000 miles is a quart every 2,600 miles, which on a 150,000-mile engine is unremarkable. The warning light is calibrated to scare you into the shop. Your notebook is calibrated to the truth.
The fifteen-dollar part that mimics a dying engine
Before anything else, check the PCV valve. It is a small valve that vents crankcase pressure back into the intake, and when it sticks open it turns the intake into a straw that drinks oil straight out of the crankcase. A stuck PCV can take a healthy engine from zero consumption to a quart every thousand miles. The part costs about fifteen dollars and takes ten minutes on most cars. I put this second in the article but it should be first in your driveway: replace it, then measure for another month before you conclude anything about the engine.
Some engines just drink
This is the part nobody tells you at the counter. Certain engines are known oil drinkers by design or by flaw: early Honda K24s, some GM 2.4L Ecotecs, the Subaru EJ25 with its whole history. If your engine is on that list and it has done it since 60,000 miles, you are not watching a failure. You are watching a characteristic. The owner's manual for some of these cars allows up to a quart per 1,000 miles and calls it normal. Read your manual before you read the forums.
Your next step, in plain language:
Replace the PCV valve and measure properly for a month. If consumption drops, you just fixed it for fifteen dollars. If it holds steady at a quart every few thousand miles, keep driving it and keep a quart in the trunk. That is maintenance. If it is a quart every few hundred miles and climbing, get a compression test. Only that reading earns the conversation about a replacement engine, and only then should you confirm fitment on Expedia Engines.
Written to help, not to sell. If this guide ever points at a replacement engine, it says so plainly — and the only place we send you is Expedia Engines' fitment search, disclosed, with your VIN in hand.