Thicker oil will reduce oil burning. My mate has a old CE lancer, engine makes rattling noise, so I put Shell HX7 10W50 and it does reduced oil consumption by half, no more noise. But I cant guarantee it will work on turbo cars, turbo core may not like thick oil that much.

Repco staff recon Pentrite fully synthetic and Shell is good, Castrol not so much, too much detergent not enough lub in it. But at the end of the day, only used oil analysis can tell the true story.

I think excessive fuel is black, oil is blue, coolant is white.

Maybe check ur PCV as well?

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MY08 STI 422whp at 1.5bar on E85, built by Diversion Garage, assembled and tuned by EvoR

Update from new owner: 375whp at 1.4bar on 98, at Tokyo Motorsport