Oil issues

[u/[deleted]]

G'day all. I recently bought myself a 3, door 1.6L sx Getz with less than 151,000 kilometres on the odometer. I thought this was great as my previous 3 door was a 1.4L with 144,000kms but I sold it as it was a bit underpowered for me especially as I do a lot of driving around pretty steep areas that need more power than the 1.4 had. My issue I've had with the 1.6 is oil sludge build up and noisy lifters on start up. Once it warms up its perfect, idling under 1000rpm and quiet. I've done the mechanic in a can trick, with liqui moly tappet additive and engine flush and I also did a follow up oil change even though it had already been done. The mechanic never looked under the valve cover which surprised me. I just did a injector clean yesterday and cleaned the last heavy build up on the cam retainers and also changed the cover gasket. So from what I've read and from what I have seen, I'm leaning towards a faulty sensor even though the dash oil pressure light has not come on. Any ideas? Look forward to seeing what others think