07-17-2013, 03:36 AM
(not an oil war post !)
With recommended oil viscosities, what matters to me is bearing surface protection and proper cooling. All other subjective considerations are secondary.
So I'll go with what a manufacturer's engineers recommend.
If Honda says for this engine: use 10W-30 or 10W-40, then that is what I'll use.
If Harley says for their big twins: you can use 20W-50 (and others), then that is what I'll use.
Not using what they recommend probably won't result in a blown engine or one that won't go well beyond 100,000 miles and still look pristine when opened up, but rather just one that gets old 'before it's time' because it could have been lubricated/cooled better if the recommended lubricants were used. That's what I choose to believe anyway (since I have no engineering data to back it up :-) ).
With recommended oil viscosities, what matters to me is bearing surface protection and proper cooling. All other subjective considerations are secondary.
So I'll go with what a manufacturer's engineers recommend.
If Honda says for this engine: use 10W-30 or 10W-40, then that is what I'll use.
If Harley says for their big twins: you can use 20W-50 (and others), then that is what I'll use.
Not using what they recommend probably won't result in a blown engine or one that won't go well beyond 100,000 miles and still look pristine when opened up, but rather just one that gets old 'before it's time' because it could have been lubricated/cooled better if the recommended lubricants were used. That's what I choose to believe anyway (since I have no engineering data to back it up :-) ).