As it has done 154k miles, some wear is inevitable . You are using approx 1/2 litre per 600 miles which is just about acceptable..

If there are no oil leaks - easily seen where you park - then a short term measure is to use 10W40 oil which was a Toyota standard before they switched to 5W30 to save fuel.

Try topping up with 10/40 semi synthetic.. and use that at next oil change.

You could also try adding one of the Oil Leak prevention fluids - about £6 per bottle which could - note could not will- reduce oil consumption if there are small leaks in seals..

Apart from that, you might have stuck piston rings which would lead to increased oil consumption..But it is more likely that the valve oil seals are worn or have hardened.. allowing oil to seep down the valve guides and be burned. (happens more when oil warm so not seen around town). The Leak Prevention fluids work by making all seals swell so if the oil seals are the problem you could see a reduction in consumption.

To conclude: use 10W40 semi synthetic oil.

Try a oil leak prevention fluid:

Wynns Engine Stop Leak is as good as any:

http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_154689_langId_-1_category**_165750

Edited by madf on 04/10/2010 at 22:07