Which is better for fully synthetic motor oil, Castrol or Mobil?

Today, the maintenance technician suggested switching to Shell's Yellow Bottle motor oil, mentioning that Castrol's oil with cleaning features might cause more oil leaks. Has anyone used lower-quality oil before? Is it usable?

What engine oil is recommended for the Jinxuan 4B11? I've been using the original 5W30 mineral oil from the 4S shop for over 5 years (people say it's like gutter oil [lol]). I want to switch directly to fully synthetic oil. Any recommendations? Some say you should transition with semi-synthetic oil before switching from mineral to fully synthetic. Is this necessary for the Jinxuan?

Which one is better, Honda Green Can or Castrol Edge?

Which synthetic engine oil do you use for the 2020 Tharu 1.4T model?

For the 2011 VW Touran with a manual transmission, it's generally recommended to use high-quality engine oil that meets the manufacturer's specifications. A popular choice is synthetic engine oil from brands like Castrol, Mobil 1, or Shell. Always ensure the oil meets the VW 502.00 specification for optimal performance.

Do you use fully synthetic oil or semi-synthetic oil for your 308?

Which is better for fully synthetic motor oil, Castrol or Mobil?

What should I pay attention to for the second maintenance of the VS7? Any tips from experienced drivers? Do I need to use fully synthetic oil? Currently, it has run 9,200 kilometers.

Do you use fully synthetic or semi-synthetic oil for your 10,000 km oil change?

Car enthusiasts, my 10-year-old 2.0 Mazda 6 has reached its mileage. Which one is better, Castrol Magnatec or Idemitsu IFG3?