Smoke and limp mode again

[20Vcqdriver]

Not sure if its a coincidence, but ever since refurbing my turbo I have had the engine jumping to limp mode at full throttle with anything over 4000rpm ish showing, the first refurb lasted 100miles before smoking like an old steam engine. Had it refurbed again under warranty and it was still jumping to limp mode but at least managed to pass MOT today first time (emmisions 137HC and 0.56CO). Went to take my son to Chester and it has starting smoking (only slightly so far) again after just 60miles use, this despite the fact I changed the oil to Silkolene 5W40 as they said it could be an oil issue. Could changing to the 5w50 silkolene stop this? Also been suggested that could be exhaust as still on the 7A 2.25" stainless system whilst I save up for the 2.75" version. Getting ECU codes read next week but any help /advice appreciated.
Anyone upgraded to a different turbo and got a serviceable K24 I could have?!!

[UrS4boy]

Are you sure the "smoke" isn't burned coolant? i.e. you might have a head gasket problem. Can't be oil if you passed the MOT sniff test on Hydrocarbons.

[s2_bo]

I seriously doubt that its the head gasket. From what you said above all fingers point at the turbo.
I dont think that the type of oil would have such a big effect. Even cheap oil runs ok and doenst result in what you said above.

Who refurbed it? Maybe the cocked it up? Thats quite possible.

[20Vcqdriver]

Are you sure the "smoke" isn't burned coolant? i.e. you might have a head gasket problem. Can't be oil if you passed the MOT sniff test on Hydrocarbons.

Took the car for the MOT day after I fitted the refurbed turbo (2nd try), and seemed to be ok then. Has only just started throwing smoke out later on today, but not all the time and tends to be on initial application of power after lift off or after oil has got to 100degrees or so. Clear (or seems to be) at anything under 70degrees.
Metal head gasket was fitted last year after head overhaul.
Has to be turbo hence why I would like to try a known servicable K24.

[Acidburn]

I always thought the oil of choice for a s2 engine was silkolene pro 10w50?

thats what I ran in mine, no smoke and ran sweet.

[20Vcqdriver]

I always thought the oil of choice for a s2 engine was silkolene pro 10w50?

thats what I ran in mine, no smoke and ran sweet.

Sounds like I'll be ordering some more oil then. Is the 50 grade much different than the 40?

[Rusty]

Xw50 for road, Xw60 for track. It's to do with the high temperatures you get at the turbo bearings and the subsequent reduction in viscocity of the oil.