Engine oil Castrol or AMSOIL

AMSOIL is good stuff, but it's expensive.

Best oil IMO is Castrol 10w40 high mileage part synthetic, usually good specials at local auto parts stores and Walmart.

I'm in LA and I use castrol oe professional 5w-40 on my rebuilt 16v. The best oil I've used so far in my mk2 and I've tried a lot (Rotella t6 5w-40 Mobil 1 15w-50 and Total Elf 5w-40) all synthetics. Try it out. You won't be disappointed.

I use 5w-40 Castrol Syntech oil in my 2010 3.6 CC. I believe that if you are going to keep the car for a long time( over 100k miles) then I would use the thicker oil for better lubrication and wear protection. Owners in warmer areas like myself should use the 5w-40 due to the higher summer temperatures which will break-down the 5w-30 oil faster than the 5w-40 oil especially after a 10k oil change period.

In my last four VWs I've run the Amsoil 5w40 Euro Spec oil and think it is good stuff. My 1.8t engines in my old Passats ran really quiet with this oil. I changed the oil in my GTi at 2500 miles and switched to the Amsoil and have had no complaints. I'd recommend Amsoil.

I've been running Castrol 5w40 in my car and have had no problems.

Castrol GTX 5W-30 with an STP filter. NY area. 178k miles with no HLA tick so far. Had some 10W-30 in it before during the winter and the car didn't like it too much, took over 3-5 tries cranking to get it started.

In my gen 3, I've used Castrol OE Professional 5w40 (the Castrol in the gold bottle that the dealer sells - oil has a green tint to it), both when I did the 5k mile change and when the dealer did the 10k change.

I also use Amsoil European Spec Mid-Sap 5W40 approved by VW

Used Castrol 0W-30 in the past with the GTI and GLI. Pretty decent oil analysis numbers when tested.