Engine oil Mobil or Castrol

All oil changes on this car have been done with Castrol Syntec 10W30 Full Synthetic and an OEM Mazda Filter.

From what I can find, Castrol makes a 0W30 longlife oil which can be used in VW engines which have sensors which support the longlife service regime. According to this regime, oil change intervals can range from 9,000 miles or 12 months to as long as 30,000 miles or 24 months - IF the sensors will allow such an extended interval.

In the early years only VW dealers carry Castrol Syntec 5w-40 oil which is where I am always getting from.

On the 16v I had I also had a cyl head temp gauge and temps dropped from 240F to about 210F when I switched from Mobil 1 to AMS, so did my oil temp drop fromt eh 250 to 215 range.

i use mobil delvac 1 5w40 synthetic oil in my 2000 beetle tdi.

did my first oil change 2 weeks ago, put Mobil1 0w-40 in... and I'm getting better gas mileage than I was on the factory oil

I used to run Mobil 1 5w30 and switched to GC. There was a nice difference, with only one side effect - the engine feels super sluggish when cold compared the Mobil 1. It runs great once warmed up though!

I've used Mobil1 (0w-40, 5w-30), Shell RotellaT (5w-40) and Castrol Syntec (5w-30) past 100k miles. Before 100k, it had whatever garbage the dealer put in. Engine still runs like a top with great fuel economy and no unusual oil consumption at 203k miles.

I'll continue to use my Mobil 1 0w-40 for another 4 years.

I had to top off once and used Castrol Syntec, which is about $3.50 where I live.