try Redline (their 5w30 is tougher as others' 10w40), or any oil marketed as "European formula" like Synthetic 5w40 or 0w40. Even a high HTHS synth 0w30, which can be tricky to spot. One worthy of mention is Castrol Syntec 0w30 (that says Made In Germany on the back) is like the only Castrol Syntec formula that is actually PAO synthetic. These engines Direct Inject the fuel on the intake stroke, and it wets the cylinder walls, some of the fuel sticks to the cylinder wall and washes past the rings as it they sweep over it and the oil underneath picks that raw fuel right up. The result is fuel dilution, and when using an already thin EC oil, will cause the oil to break down even further than it should when it gets superheated, such as running through the turbo cartridge. Direct Injection cars (all) suffer this problem, and thas why oil selection is even more nessecary.
High HTHS rated oils stand up to dilution much better than EC oils, which is why no diesel or european turbo engine uses 5w30, EVER, 5w40 minimum, and they have to meet those manufacturer's proprietary specs.