Engine oil Castrol or OEM Mazda

I happen to use Castrol in all my gasoline powered vehicles and have had no oil related issues. Given that VW promoted Castrol and, more importantly, that I prefer Castrol in general, I’m staying with Castrol when I can... I've had no oil loss in the Tig with Castrol and see no reason to switch to a different brand just because some MBAhole behind a desk made a profit driven decision to switch suppliers.

I use 15w40 GTX Diesel Castrol oil, it works.

My 10k UOAs on Castrol 5w40 were just fine, but VW 504 is mid-saps so it might not have as much staying power even thought it's "better" oil.

Our Tig is coming up on it's 4th change (every 5K) and hasn't lost any significant amount between changes. So far all changes have been the 508 spec Castrol 0w20.

I really like Castrol oil. I used the VW High Performance twice, and it was fine, but I still preferred Castrol.

The approach to go with 10W40 is absolutely right - from my experience the best oil for that kind of engines! Take an expensive Castrol Magnatec Oil and it runs well.

As an aside, all the oil used to be Castrol and has now transitioned to a VW boxed product produced by Mobil 1. THAT is the correct oil.

I've switched to Castrol Magnatec 10W-40 which seem to do better wrt oil pressure.

Try using 5w30 castrol from walmart black container with green writing, since switched been driving 2.7k with in 2-3 month oil on the same level

I run 5w40 syntec and I eat about 1/2-3/4 oil every 5,000 miles. It will eat it more if I drive it really hard.