Engine oil Castrol or Lucas

When it comes to oil I have one thing to say. Use Valvoline or Castrol 3000 for conventional 5 to 7000 for synthetic,. If you do this and take good care of your vehicle your car will go 200,000 to 300,000 miles.

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.

I personally used to run mobil 1 0w-40. as you said its super thin and seemed to just barely get the job done. Recently switched to castrol SLX 5w-30 and I am decently pleased with the first two changes.