Engine oil Castrol or RED LINE

That's what the dealer and I use. Castrol 5W40

A few years ago Castrol decided to dye all their Magnatec oils green... it was pretty dark green as well.

I used to use German Castrol 0w20 in my Volvo and it was green too.

I use strictly Redline oils for all my fluids except premix. Engine oil is Redline 10w40.

I use 10w40 full synthetic oil, and only the best quality stuff. Valvoline, Castrol, Pennsoil, Mobil1, Idemitsu end the like. Before my rebuild, I was using Idemitsu Rotary blend but switched to Castrol GTX. The GTX semi synthetic blend had a slightly lower oil temp and lasted longer per oil change than the Idemitsu, indicating that it was lubricating better.

I think you will find out Castrol EDGE® Euro Car 5W-40 A3/B4 Full Synthetic is a better all around oil then and oil I’ve owned Volkswagen all my life and that’s all I’ve ever run in my vehicles never had a problem and if you want to run the 10,000 miles between oil changes this oil will handle it

I've always run Castrol with no issues. The biggest thing is to make sure that whatever oil you use meets the spec required by your engine.

I use Castrol GTX full-synthetic 10W-40, as I live in Texas where the average temperature is hotter than the rest of the US and oil weather varies drastically. During the summer, I've considered bumping up to 15w-40 due to how hot my startup temps are on a "cold start".

Redline recommended 10w-40 Full Synthetic for my 1.8 solid lifter JH turbo application and the tech guy suggested modern synthetics don't cause seal leakage (like OG synths of 25 years ago) and holds up way better than the 40w rating in hot temps and protects much better when cold than even the current crop of Castrol 20/50 dino oil I was running. I swapped over the M81 to the same Redline oil and have not yet noticed any new oil leaks yet.

I tried the redline 5w30 previously which has very high levels of moly (>800ppm) and the results were not as good as the moly-less 5w40.