my Mazda 5 losing oil ,under the car is clean , i took the car to a mechanic but he could not find any thing ,
Well, if it isn't leaking the oil, it is probably burning oil. How much oil do you "lose" between oil changes? How many miles on the car?
it loses about 2.5 liter every 2.400 km .i checked the exhaust ,it was not too black .
by the way thanks for answering .
Well, that's substantial oil burning. You probably have worn piston rings, but possibly worn valve guides. You can check your engine's health with a compression test. You can just get in the habit of checking/filling oil when you fill your gas tank. If you don't run low, you're OK until the oil messes up your catalytic converter (it would probably need to get considerably worse to do that).
https://www.youtube.com/watch?v=ovvXnd7AhiU