The Truck & SUV designation is just poor marketing.

If you use the Mobil oil finder on the Mobil website, you will find that no Mobil oil meets the recommended viscosity and the required VW/Audi oil specs. Mobil will say you may be able to use M1 0W-40 or M1 15W-50.

In my opinion, M1 5W-40 (idiotically marketed as "Truck&SUV") is the best M1 choice for the 12 engine, as it offers a near ideal viscosity range. Be advised that this oil does not carry the required VW/Audi approvals. However, this does not mean it does not meet or exceed the requirements of the 12v engine.
If you expect sub-frezzing temperatures, you may want to go with M1 0W-40. My engine didn't sound good once hot with that oil, though. Lots of rattling, which I don't hear with M1 5W-40.

You have other oil options (VW502.00):

Castrol SLX 0W-30 (make sure it says it meets VW 502.00, not all SLX say that!)

Castrol 5W-40

LubroMoly Vollsynthese 5W-40

Pentosynth 5W-40

Chevron 5W-40

and I still do.

Now we can get the VW502 spec in the Belgian Castrol 5W-40. Nice, because A, it meets the specs, and B, because they dropped the ca $8 price to under $5 a quart.

From seeing the VOA (virgin oil analysis) on that oil, I'm inclined to say that M1 5W-40 is a better oil, though.

any of the 5w40's is sufficient.

otherwise most of the oils don't meet VAG valvetrain requirements... hence ticky lifters etc. My lifters are already shot as I believe they're 11 years old, but if you replace 'em run the proper oil & they'll be good for a long time

check yah later

... has to do with how fast or slowly the lifters fill with oil, which is mostly a matter of viscosity. For example, when hot M1 0W-40 made my motor's valves clatter when hot. That's why I didn't care for the 0W-40. It's thin sauce.

The pertinent valve train wear test is PV-5106.

Here are the required tests and specs to pass VW 502:

sulfated ash: 1.5% max
HTHS: 3.5 min
seal compatibility: PV-3344
valve train wear: PV-5106
VW T4 test: PV-1449
sludge: M111E

The VW 502 spec requires very demanding high temp/high load testing in a test that runs for 248 hours -- with no makeup oil added.

Cam lobes, not ear lobes! ;-)

There are some blends, though. And as you said, the M1 is synthetic.

so do i understand now you use 5w 40 syn M1

It's the best full synthetic 5W-40 I can find for under $6 per quart. Though it doesn't carry VW 502 approval, the relevant specs (HTHS, sulfated ash), exceed the requirements for VW 502. I plan on having a UOA done on this oil in a while.

If you are a stickler for VW specs, Castrol 5W-40 should be a good oil (group III, semi-synth).

If cost were no issue, I'd use Red Line 5W-40, but at about $8 per quart, the price is a tad steep, and the 100% ester content worries me (possible oxidation issues). Red Line oil does extremely well in VW/Audi engines (according to UOA).