Liqui Moly oil

Hey guys!

I curious have any of you tried Liqui Moly TOP TECH 4200 oil. It seems to have very good reviews online, especially on amazon.

In my 1.9 TDI PD (non-DPF) for the last two years I have used Shell Helix Ultra ECT C2/C3 0W-30, according to the recommendation from their Lubematch online. However, the engine is quite noisy lately and I'm starting to head some strange but very slight buzzing sound around 3000 rpm and up, kinda like the oil isn't doing its job very well. Recently I pumped some oil out through the dipstick tube and I sent the sample to Blackstone Labs, now I'm waiting for the sample to arrive there and for them to test it. I'm no oil expert, but when I took out the oil it was almost as thin as water (at room temperature). It was super dark and it kinda looked like there's some soot it in, and it had a very strong burnt scent. I don't know if this is normal or not, I guess the oil analysis will tell. I had the oil changed just 2500 kilometres ago.

In case if I need to change the oil, do you think Top Tec 4200 5W-30 would a good substitution? Or perhaps Top Tech 4600 (it's approved for 505 01 but not for 504 00/507 00)? I also plan to mix in some Cera Tec.