Engine oil AMSOIL or IDEMITSU

You don't need to add any more additives to modern day oils. You said you will be using Mazda 0W-20 oil? This is one of the best 0W-20 oils on the market. It is made by Idemitsu for Mazda. It has very high Viscosity Index of 221. Most 0W-20 oils are around 170. This means it is one of the lightest 0W-20 at start up. This is what you want in the winter.

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

Amsoil 10w40 and there 20w50 non race oil it says right on the bottle it has a heave zinc compound for extreme use. I use the 10w40 in my Rocco 16v my wifes mk1 gti , and a lot of other vehicles. No upper end noises on any of them. Worth it weight in gold!

I've been running the AMSOIL 5w40 in my cars exclusively for the last 5+ years and it has lasted well and held up to abuse as well.

For those of you having a hard time finding VW spec. oils and you desperately want to stick to the 5w-40, try your local lawn mower, or small engine repair shop. In my area only they stock the 5w-40 synth. VW 502.00 oil - they used to get Elf/Total, but recently moved to Amsoil.

I've been running 12k-20k, oil & filter change intervals with Amsoil since 1978 (mainly in VW/Audi engines) and have never come close to wearing out an engine. When I sold my 1990 Audi 100 with 260k miles, it was still only using a quart of oil in 10,000 miles.

I've been told the magic elixir for the VR is 20w50 Amsoil Not sure I can verify that just yet but my VR is a bit quieter with it since I added it

I used Amsoil 0W-30 Severe service oil in my Jetta 1.8T for the first 120k miles or so. No problems, mostly 5-7k oil changes except when I was commuting from Ct to Boston.

Amsoil made the engine idle much smoother than any of the other oils have but every oil I've used but Mobil has been good as far as life and burn-off goes.

I've been using amsoil for the past 2 oil changes. No complaints, car seems to idle a little better and cold start sooner.