I've been reading about the 0W-20 oils and have seen a lot of people say it is needed because of tighter tolerances, so I decided to find out what oil is recommended for our engine somewhere else. I e-mailed toyota of Australia and asked them what oil is recommended for the Prado with the 1GR-FE engine, so they sent me a couple of the pages out of the owners manual which showed 5W-30 as the lowest grade for extreme cold with the other options being 10W-30, 15W-40, all the way up to 20w-50. So, it makes me think that over here the main concern is fuel economy. Please don't flame me, I'm not saying that there is anything wrong with 0w-20 and 5w-20 but after finding this out I don't think I would be afraid to run a heavier oil if I was doing a considerable amount of towing. That being said there are probably a few hundred thousand cars running around with 0w-20 towing and getting ran hard in extreme conditions with no problems.