Alright then, this is something I've been trying to figure out and don't quite know how to deal with.

I own a 97 Sunfire with a 2.2L engine and 214,000 kms. Until the last oil change I've been using regular motor oil, Castrol 5W-30 and AC Delco filter and I've had no problems with oil consumption at all. I'd put in about 4 liters and when the time comes for an oil change I would get 4 liters out.

The last oil change, about 3.5 months ago, my mechanic ran out of the regular Castrol and upgraded me to a High Mileage Castrol 5W at no extra charge. Ok, whatever. All of a sudden over time as I check the level I find it decreasing. Today I checked it again and the level is only 10% into cross-line area on the dipstick. I've never seen this car use that much oil in 3.5 months. There is no oil leak anywhere, not on the floor of anywhere on the block, and the valve cover gasket was changed a few months ago.

What's causing this excessive consumption?

Thanks!

I have found that with various brands or special versions like you stated sometimes they may not work as well as the standard you may use.Example I have a 87 mazda pu always used the valvoline 10/30 or 40 and tried the high mileage stuff by valv and mine actually used some oil unlike the standard.Same situation no leaks just use.Granted mines got 187,000 so some use is normal but,saw it use more with the change.I stick to the same if the eng likes it,stay away from synthetics for mine,does not like it.I think run it till ur next change and go back to what u norm run.That's my take on it.

It's good to know it's nothing unusual. I topped it off today with the same type of high mileage oil just to keep the proper level until the next oil change and will go back to the regular stuff. No point spending extra money for it, I change the oil and filter every 5000 kms anyway.

they claim that it rehydrates dryed gaskets and seals and that a little consumption at first is normal, however i dont believe in a mechanic in a bottle so whatever