I don't think there can be a blanket statement for all engines that thicker or thinner is better without a trend established on UOA's for a particular oil for a particular engine. I had great success running 5w20 in my Dodge Journey's engine which called for 5w30 previously. 4ppm Iron and 0 on all other metals after 9K is excellent and would indicate that parts are being kept separated with this thin oil. Would it have done better on a 30wt as previously spec'ed for this engine? I doubt it considering how low my numbers were.
What I'm getting at is that I would start with the owners manual, establish a trend and the move up a weight and see how that affects the trend. Then switch brands and try various weights and see how that affects the trend. All engines are different, all oils are different and we can't blanked that 20 weights are evil and part of CAFE conspiracy and 30 or 40 weights are the way to go without proper evidence. That's my take on it.
What I'm getting at is that I would start with the owners manual, establish a trend and the move up a weight and see how that affects the trend. Then switch brands and try various weights and see how that affects the trend. All engines are different, all oils are different and we can't blanked that 20 weights are evil and part of CAFE conspiracy and 30 or 40 weights are the way to go without proper evidence. That's my take on it.
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