Originally Posted By: fredf
So, not to hijack this thread, but I have a 2011 VW GTi which I just put GC in because from what I got on BITOG was that is would be better than straight Castrol 5W-40 in general and with the 0W it would be particularly better for winter (I'm in Canada).
Now I'd reading that Mobil 1 0W-40 may be better for winter than GC and might even have a better add pack for my engine.
I know a lot of this is just opinion, but would you guys, in general, consider M1 better than GC for my engine?
As I have mentioned M1 0W-40 is lighter on start-up at virtually all temp's as high as 25C. The reason is M1's much higher 185 VI vs only 167 for GC. This applies to start-up temp's down to about -20C. Below that you really have to look at the extreme cold viscosity stat's like MRV @ -40C and CCS @ -35C. Mobil provides those figures but Castrol doesn't.
You're in Canada but you haven't mentioned where and therefore what is the coldest temp's that you will be starting your car?
If you're in the GTA as I am, then M1 0W-40 is the better choice, but if you're further north and you may be starting your car unaided at -40 degrees then GC could have an advantage but without the spec's we don't.
BTW, if using a non specified oil doesn't bother you, in Canada we have a number of heavy (HTHSV 3.5cP+) 0W-30 oils from which to choose. Petro-Canada, Imperial oil and Shell Canada all have suitable offerings that are both lighter on start-up and cheaper than M1 0W-40. My favourite is the PAO based Mobil Delvac Elite 222 0W-30 (nee Esso XD-3).