5w30 - VS - 5w40?

I ran 0w-40 in both current my Kias one summer a few years back, both cars call for 'recommended' 5w-20 oil.
With 0w-40 cars felt 'heavy' during driving and engine was getting a tag hotter so that was first and last time for it, went back to 5w-30 year around and all's good.
 
No, it will stain your engine purple!
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Any other 5W-40 will be fine though...
 
I ran 0w-40 in both current my Kias one summer a few years back, both cars call for 'recommended' 5w-20 oil.
With 0w-40 cars felt 'heavy' during driving and engine was getting a tag hotter so that was first and last time for it, went back to 5w-30 year around and all's good.
My little Accent zips around like a fast go-kart regardless of viscosity used.
 
People always said modular motors had too tight of oil passages for thick oil. Just internet rumors of course. My neighbor was a contractor and ran 20w50 with STP in a 5.4l van because it was hot in Arizona. Had 200k+ miles when he moved away. Said he never had an issue.
schaeffers had a million mile 5.4 with I believe it was 15w40? I wouldn’t think that possible if the passages were causing oil starvation

It is a 2003 econoline so that may be different
 
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schaeffers had a million mile 5.4 with I believe it was 15w40? I wouldn’t think that possible if the passages were causing oil starvation

It is a 2003 econoline so that may be different
No engine has too tight clearances for thick motor oil, oil is a liquid and will find it's way into any small space it can, the only thing that could possibly stop it is surface tension, which is low in oil.
 
If "passages are too small for proper lubrication", then journal bearings wouldn't last very long at all. Journal bearing "passages" are basically the smallest passages in an oiling system
 
A 5w-40 is very good oil for a VK56de (the engine in your truck).
In foreign countries Nissan used to recommend this fill as standard for VK series engines.
 
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