Oil “flowing fast enough”

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So would a 5w20 and a 5w40 behave the same at cold temps since both share the 5W part?
In practice, typically NO.

As the 5w - is tested at temps below MINUS 20 deg F. Note The "w" in 5w designates Winter capability in a Multi-grade oil.

The 5w20 grade will be considerably LESS viscous than a 5w40 grade at, say, 10 degrees below freezing.

This may mean less windage and parasitic losses in the engine during the auto's warm-up phase effectively improving drive-abilty moderately and fuel consumption somewhat.

@kschachan reply is factually correct, of course, I'm am merely attempting a layperson "flesh out" of the subject
 
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Yep, bought a nice looking $200 86 Camry that was smoking like a mosquito fogger. Had some cracked rings or piston grooves, so replaced them all in the driveway. Sold and delivered 800 miles afterwards so I know I did a good job.

View attachment 115683
Atikovi Curious at to what type of hone did you use on the cylinders. Good job! I didn't realise you got that deep into these fix-an-flippers - Ken
 
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Atikovi Curious at to what type of hone did you use on the cylinders. Good job! I didn't realise you got that deep into these fix-an-flippers - Ken

Used a hone with the 3 stones you stick into a drill. This was over 15 years ago so details are fuzzy.

70Cylinders honed.JPG
 
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It’s not my car, but the topic was that the engine would “blow up” if a 40 weight was used. You say it won’t, I say it won’t either. The engine, for all purposes is toast. The guy is trying to get another 70,000 out of it without repair. I suggested going to a 40 weight. Was told the engine would blow up because of “flow”.
I guess what I’m asking is, what is the difference in viscosity at operating temp and will that cause an engine to blow up?
It won’t.

And flow is irrelevant.

It won’t blow up.
 
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Reminds me of an old Nova my best friend had. That car would use almost a quart every 100 miles. When he started it up, it would spray you with oil out the tailpipe if you were standing close enough. That car kept going and going!! He always kept a case of Shell 20W50 in the trunk everywhere he'd go (that was the cheapest oil he could find back then, came from Sam's I think). He eventually gave the car away and told the new owner to check the oil daily. One day driving home he saw it on the side of the highway with the hood up :ROFLMAO:
 
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Well one could argue that at 2.5qts per 1000 it’s already blown up…
Agreed. I would try doing one drain and refill with a significantly thicker oil to see if it reduces consumption at all. But if this fails I would be using carefully collected used oil for this vehicle's top ups.
 
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19EEBB6A-E918-4427-B805-73A40C702BA8.jpeg

If a thicker oil was bad for your engine, your engine wouldn’t survive a single winter .
Even a thin 0w20 in the winter would probably be thicker than 20w50 at summer temperatures .
 
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Picture after honing.
I was interested if you used a ball hone or a 3 stone. I think the hone marks look weird due to it being old digital photography/jpeg engine that gets confused with animal fur ... and hone cross hatch.

Either that or it was a coarse stone and briefly worked with slow plunges.
 
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