Best oil IMO is Castrol 10w40 high mileage part synthetic, usually good specials at local auto parts stores and Walmart.
Owner reviews for engine oil
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 just switched to Mobil 1 for the last interval and the engine ran much better on it.
I have always liked and used Redline in my non-German cars. In my German cars, I have used either Lubro Moly (also known as Liqui Moly) or Pentosin, both in 5w40. Great synthetic oils, imo. I would not run Mobil or Castrol products if you gave them to me for free.
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.
I used 5w40 Mobil 1 Full Synthetic in my 08 Passat. Had such great results, I carried it over to my 12 R Line.
Speaking of Rotella, Here's a personal observation of mine. My beater Saturn 1.9 has a lifter tick (not fixing it, don't care), so I just put in Rotella T, and it quiets it up a bunch!
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.
ROTELLA T6 - Instantly i noticed a very nice purr from the motor. Its a heavy oil and with stabilizer (in this case thinner than the oil) It warmed up slower, meaning that it was absorbing more heat. No extra start up noise at all. The biggest gain from the Rotella was hot weather stability. It seemed to perform the best when you drove the car hard! Hot weather didnt affect the engines power anymore, and that made me really happy. Turbo lag was increased slightly, and the engine revved slightly slower, but remained perfectly stable. I loved this oil for protection, its really good for hot weather!
In my VW's I do 5K oil/filter change just to be safe and always use VW spec oil. I do not have analysis done on my used oil, it may go farther but $50 for Ravenol VMO 5w40 and OEM filter is a lot cheaper than an engine rebuild.
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