if one cylinder is at 90 is the engine gone?

is it possible to fix the cylinder if all others are working?

Is it the rings or a burnt valve? A burnt valve could be fixed but if it was the rings and the car runs OK then I would drive it for a while and then rebuild it. How many miles on the engine?

Is it losing coolant? Could be a bad head gasket also.

Hi thanks for the responses...mechanic didn't specify what was the problem ..he only said that the cylinder was only at 90, the other 3 are between 147 and 153. The car is a 2005 legacy in beautiful condition, it breaks my heart to junk it. Its not loosing coolant but is blowing through oil.

the engine has 156,000

the mechanic checked coil and put new plugs in...still no change

As a last ditch effort to get more miles out of your engine there are two products you might want to try - Liqui-Moly Engine flush and motor oil saver, you can buy both on Amazon. You might also try running heavier oil such as 10W-40 or even 20W-50.

An '05 GT is a TURBO 2.5; as such I suspect you have a bad ring instead of burnt valve,but who knows? The tremendous imbalance in that head should be felt as a strong vibration, eventually resulting in failure. If you're above 20F this winter I'd try running 20w50 and seeing if compression pops up a bit. If colder, use 10w40. If you prefer synth to cool the turbo use only 15w50. Note that 2005-06 GTs have a very high failure rate: do NOT rebuild, as eventually the turbo or a rod will fail anyway.