10w30 seems thin for the l/ z series. I switched to 15w40 castrol as its lpg ok use and has better properties than the shell I used in a pinch. The shell was 20w50 but mixed with 5w30 in a oil dip stick mishap that saw oil come out the dip stock under high revs

Im using the Penrite HPR30,(same as bigE)in my A14 turbo. What i have found really good is the oil additives you can get. I like the (Nulon or Lucas) brands.

Start your engine and add the good stuff while the motor is running, you can hear the tappets go quieter in front of your eyes. The motor runs smoother and consistant, also extending engine life.

I have been told these can even be used in gearboxes and diffs.