White smoke after 5k rpm

[lemmingjames]

Ive been looking around at have a feeling that the head gasket is going (excessive oil consumption) but lately when ive been booting it past 5k rpm after its had plenty of warm up time) i see a puff of white smoke in the rear view mirror.

Ive read that switching from 10w-40 to 5w-40 can do this (before it was requiring 1l every 750 miles = normal consumption, then i changed it to 5w-40 and its drinking it plus theres an occassional leak above the sump plug though two garages say they cant find a leak).

So any ideas or am i about to be bent over/new engine required?

Its a Forester XT 2.5 (2005)

Thanks

[Ved]

Checked the coolant?

http://www.subaruforester.org/vbulletin/f87/when-i...

[lemmingjames]

Thanks for the link, ive since tried it a few more times and no more smoke either with the engine just turned on or being run for 10+ minutes.

However, the garage that undertook the MOT, over filled the coolant bottle so it was about an inch from the top. So have sucked out the excess down to the full mark (might have slightly contaminated it via using an oil syringe but the oil 'slick' on top is minimal/non-existant).

Will check again and see but it wouldnt surprise me to learn that its leaking past the turbo as you used to be able to smell oil from the outside.