Dan, I was using Castrol 10w60, which was what MMS serviced my car with up to about 50ish thou km. Found that it burned at a normal rate. Car at this point did the odd cruise/skidpan and rest was daily driven.

Mods went in (which are similar to yours, just missing the turbo), started using Stehnic from that point onwards and burns at a normal rate as well. They use Total 10w50. I try to service it every 5-6k km. Car currently has about 81ish thou km

Go see Doug @ Stehnic if you want to try the Total. He should have some there.
If not, try a 10w-40. Brand wise im not too sure or cant remember from some of the threads.
Find something that works and stick with it!

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