Imaging my chagrin at being told by a dealer that the 2.0lth Turbo engine has a known oil use problem due to a "special designed" cylinder/piston relationship that require more clearance blah
That's a misleading statement of partial truth. The goal for an engine designer is make the engine last as many miles as possible. In past times an engine was considered worn out after 100K miles or less, whereas today life should be around 200K+. It was also realised that most engine cylinder wear ocurred when it was cold.
Combustion engine internals haven't changed much, so how do they get longer engine life? Some bright designer spark came up with the idea of using oval pistons in round cylinders. Oval pistons are made with expanding metal cast into them. When the piston is cold and more likely to wear, it is oval but when it reaches normal temperature the metal in the piston expands and the piston becomes circular and a tighter fit inside the cylinder
Now we have a different scenario that can cause an engine to burn oil for most of its life: If the engine is 'babied' from new and used for infrequent short journeys, the oval pistons will let past more oil UNTIL the engine is hot. Shopping moms often complain about their cars using too much oil! When the oil leakage builds up through regular cold starting, piston oil control rings get gummed up and stick. From then on the engine will burn oil however hot it gets. I have seen the results from this problem after an engine teardown. The cylinder may show very little wear but the piston rings are gummed up with burned oil. Those driving their cars hard do not have this problem. Look at how your car has been driven from new before criticising the brand. Most modern car engines now use the same design. A 2l gas engine is a big beast to heat up and oil burn more likely. If you are a local mileage user, you are better off buying a vehicle with a smaller engine. Big and turbo is not always best!
The damage has already been done caused by soft driving, short journey use, or frequent cold starts. Better to drive the car as if you stole it (within legal limits!) but what can you do now?
1. Engine teardown, replace piston rings and drive the car harder in future or let your younger kids drive it once a week.
2.Engine cleaner additive: This only has a small chance of success. You pour it in the fuel when the tank is < 1/4 full, then drive the engine hard at higher than normal rpm. The additive makes the fuel burn hotter and 'may' remove some of the piston ring clogging. There are also some additives that can be poured into cylinders and left overnight, but still no guarantee they will work.
There's a misleading 'Myth' from old timers about 'Running in' engines which isn't so relevant with modern engines. I drove rental cars for many years, some arriving new with only a few miles on the clock. None of them ever used oil between service intervals. It's too late if the damage is done but also look at your oil specs. There are some ultra low SAPS rated oils around which I try to get for my Tdi diesel.
If your car whatever its brand uses excess oil, look at how it has been driven. 'Low mileage one lady owner' may not be the car you may want to buy any more!
