You'll find a majority of people on here are using 10w40 AT LEAST.

 

I'm using 10-60 in my forged engine.

 

same here, fuch's 10w60. never needed a top up at all on my forged 2.5

 

 

So Doc, did you get to the bottom of this?

 

5-30W oh dear -that's expecting issues

Swapping from 10-40 to 10-50 Synth saved me a bit of consumption.
From >2 down to 1 litre per 000 km And my ring lands on mine were already shot.
Compression was also down to 6 bar on all 4 pots. Still runs though. Just not very crisp.

The forged motor is ready to go in though. You should expect to pay 3500 for assembled short block. And a do it yourself head swap. If you go forged, which was my decision after 3rd engine (Spec 350Bhp) then do consider Fully Synthetic Ester core 10-50 or 10-60 to protect it. My next build will be run 2 hours in workshop varying revs off load , with mineral oil like 20-40 Castol GTX Then again short run in 100 miles before going to the Ester core 10-50 .