Car loosing oil without a leak

My car is a Toyota Vitz 2007 and it has done 80k miles now. Recently I noticed that the oil level of it is getting reduced. I checked whether there is a leak but I couldn't find any. When I start the car in the morning and step on the accelerator, I get a white smoke. But no smoke comes after I drive the car for a while.

Also, one more thing I noticed is that the fuel economy of the car has also dropped recently by about 20%.

Only warning I get when I scan the engine is rough idling.

Can someone help me figure out what is wrong?

your pcv system could be sucking some oil in and burning it when your driving, could also cause a rough idle. has the car had a tune up recently? if you can get the rough idle problem fixed that might solve your oil issue, if not might need to do a leakdown or compression check to see what the internal engine conditions are

Hi Crvett69,

Thanks a lot for your answer.

I got the car checked by a mechanic and he checked the engine compression and compression is OK. He topped the oil level and asked me to drive for some time to measure the oil reduction rate.

When searched on the internet, one other reason that is mentioned which causes the engine to burn oil and produce a white smoke in the morning is oil leakage from valve seals. Is there a way to identify whether the problem is in PCV or is with the oil seals?

One more thing, the mechanic told that he noticed some oil in one of the spark plugs.

Thanks

oil smoke should be blue, white is usually condensation that formed in the exhaust as it cools down. was the oil on the spark end of the plug or had oil on the porcelain? if its just on the porcelain thats a indication the valve cover gasket is leaking

Thanks Crvett69, I'm not sure whether the oil was in spark end or porcelain. What could be the reason if the oil was on the spark end?

if its on the spark end it sucking it in through intake, valve guides or past the rings

Thanks a lot Crvett69 for your help.

Hi Crvett69,

Is there a way to identify whether oil is coming to cylinder through intake, valve guides or piston rings?