Engine oil Shell or Mannol

OP I have the same car and engine as you, I've been using the cheap Mannol stuff, whichever is cheapest. Also whichever the cheapest oil filter is from ECP at the time. Car is currently on 120k and I've been doing this for at least 5 years and it hasn't eaten itself yet!

You can actually get decent quality oil which is not from an expensive brand for pretty cheap, particularly if you buy a 20l jug.

For example, Mannol offer fully synthetic oils which meet OEM specifications

Been using Mannol 5w30 Full Synthetic for past 35k miles now without any issues.

Shell Rotella T6 5w-40 in my 09 e90 335d (m57)

Supposedly should be changed every 13k miles but I do 7500 to hopefully help extend the life of the timing chain.

I’ve a 01 330ci with 284kms on it and I’ve been running Rotella 5w-40 T6 for a few years and it’s been really good. Keeps it good and clean for 10k change intervals. I probably end up adding 2-3L over that time, which was a vast improvement from when I got the car 30k ago.

I switched from Castrol Edge 0W-40 to Shell Helix Ultra 5W-40 on my E46 325Ci and feel it runs a touch better and doesn't burn as much oil. Before I was adding 1L per \~3000km, now maybe 1L per 5-6000km...

First impressions - engine is noticeably quieter and smoother at idle. Engine temps is lower by 1 line. slightly better throttle response. As for fuel consumption, i have to drive more my usual route to know if there is an improvement.

For the UK, cheap and good: Mannol Fully Bi-Synthetic Engine Oil Longlife 3 5w30

The car runs well, no problems starting up, no significant oil burning.

Rotella T6 0W40.

I've used a number of different oils in my XS400 over the past couple years, can't say I've noticed much of a difference other than when I used a 15W40 the engine was a lot noisier, going back to 20W50 and the engine quieted down a lot.