I have a 2003 Honda Civic ex 5-speed with nearly 270,000 miles, well maintained but head gasket blew. Use vehicle for DoorDash and Uber Eats and Amazon Flex deliveries, average 5000 miles a month. Was using about 2.3 quarts of oil every 5000 miles, some minor leaks but no noticeable blue smoke. Head gasket replaced with head completely gone over at machine shop (head milled, valve seats polished and valve guide seals replaced and car runs very good maintaining perfect coolant levels and temperatures (slight hesitation in mid throttle under load, no codes) but now I lose almost 1 quart every 1000 miles but still no noticeable blue smoke and nothing shows wet under the car nor on the ground. Oil consumption less if I leave the car idling during deliveries. Could this be PCV and if stuck open why no smoke?
Your piston rings are worn out. I would get a compression test, wet and dry to confirm the oil consumption. You could try and see if replacing the pcv valve helps. Good luck.
Yes, a clogged PCV valve will increase oil consumption. Autozone (as an example) sells a PCV valve for your car for less than $10 - yes, replace it, it could save you $10 and more on oil.
The reason you have no blue smoke is because your catalytic converter is burning that oil up cleanly, as it was designed to. Thankfully, it survived the head gasket problem. Actually, if you had a Kia or VW, the dealer would tell you that 1000 miles per quart was OK for their NEW cars.
https://www.youtube.com/watch?v=QhtuxS3StrA
Was using about 2.3 quarts of oil every 5000 miles (...) Head gasket replaced with head completely gone over at machine shop
Piston rings / pistons / cylinder liners should be addressed during a rebuild, now you don't have much to do about it.
GENERALLY, if your engine burns oil AND blows it's head gasket - just get a used engine instead.
Could this be PCV and if stuck open
A PVC that's stuck CLOSED will add some oil consumption. replace it, it can reduce it by 20%-30%.
why no smoke?
To see blue smoke you'd need to actually have extreme oil consumption - much more than 1L/1k miles.
At 1L/1k miles you're probably at the point where there are oily deposits on your tail pipe.
After you replace the PCV valve (and if possible clean the oil separator), you can do a wet/dry compression test to see just how bad the engine is. A regular compression tests, tests how bad the cylinder are compared to each other, a wet/dry tests how much compression overall is lost.
