Thicker is better in my opinion.

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We switched my girlfriend's Sonata to 5w30 from the original 5w20 on the cap. The same guy changes the oil on it every time (my friend I used to work with). I would do it myself with synthetic but we want the receipts since the engine is under warranty/recall for another 2-3 years because of the rod bearing issues. I probably should have gone with 10w30 in the summer months since it gets changed every 3 months, but that could just squeak it past the 10 year warranty before it seizes up.
 
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Originally Posted by BLND1
Toyota specs a wide range of oil viscosities for varying temps in its 1GR-FE (4v DOHC V6 - Tacoma, landcruiser, Hilux, 4Runner, etc...) on the world market. But only one per vehicle type in the US. CAFE requires US manufacturers provide the oil viscosity used for CAFE testing to be printed in the manual and on the fuel cap. Hence why you tend to see only a single viscosity on a majority of newer cars sold in the US. It's ridiculous that an engine that specs 5w30, 10w30, 15w40, and 20w50 in Australia ONLY specs 5w30 in the US. Sure there might be differences but I'll bet the ones that matter, I.e. bearing clearances, etc. are the same. If your usage tends towards "severe" or your annual average temps are high, I don't see an issue with a heavier oil. Let's not pretend like 0w20 is anything but a CAFE required crutch to eek another 1/2MPG overall for manufacturer fleet totals. Manufacturers are building many of the same engines for other markets and recommending thicker oils. A little common sense goes a long way.
Very well said sir; better than I could have said it. Hopefully you won't mind if I steal a piece of that post for my signature… With full credit to you of course
 
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In my celica i went from the owners manual specified 5w30 resource conserving oil to 5w40 fully synthetic shell helix ultra. Result was on the 5w40 engine didnt rev up as quickly felt as if it was bogged down. Engine was quieter however it warmed up faster too. Dumped the oil after a week of driving and went back to the 5w30 resource conserving oil. The 5w40 is at 100c was a bit over 35 percent thicker than the 5w30. 9.8cts vs 13.5cts. Was night and day difference in this application. My guess is bigger engines dont see such big differences in oil grades but small engines do.
 

SR5

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Originally Posted by slybunda
My guess is bigger engines dont see such big differences in oil grades but small engines do.
That would be my guess too.
 
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I experienced the same thing in my small Elantra and went back to 5W20 synthetic where the engine ran more "free" than with heavier weight oils .
Originally Posted by SR5
Originally Posted by slybunda
My guess is bigger engines dont see such big differences in oil grades but small engines do.
That would be my guess too.
 
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Originally Posted by slybunda
In my celica i went from the owners manual specified 5w30 resource conserving oil to 5w40 fully synthetic shell helix ultra. Result was on the 5w40 engine didnt rev up as quickly felt as if it was bogged down. Engine was quieter however it warmed up faster too. Dumped the oil after a week of driving and went back to the 5w30 resource conserving oil. The 5w40 is at 100c was a bit over 35 percent thicker than the 5w30. 9.8cts vs 13.5cts. Was night and day difference in this application. My guess is bigger engines dont see such big differences in oil grades but small engines do.
I would agree that it's likely much more noticeable on smaller engines. My v8s also make it harder to notice a difference because they are carbureted and we have such frequent temperature variations here, humidity etc. that my cars horsepower and response will change from one day to the next. I never thought to pay enough attention when I have changed grades and actually drove the car immediately after.
 
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Back in the 80's I would often run 20W50 in a 4 cylinder Pontiac 6000. Car started fine in 20 below temps. Car did not die to to engine oil failure and I sold it to an ex girlfriend.
 
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One application I know doesn't like thick oil, particularly on in cold weather, is older Ford small blocks. A lot of people would put SAE 40 or 50 in it, it would be 30*F outside, and they'd go start it up, immediately run the dog out of it, and then have no oil pressure because they snapped the oil pump drive. The OEM pump drive in those cars is notoriously weak. Every SBF I've put together, I've put an ARP pump drive in it, even if it was just a stock rebuild.
 
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Originally Posted by ChrisD46
I experienced the same thing in my small Elantra and went back to 5W20 synthetic where the engine ran more "free" than with heavier weight oils .
Originally Posted by SR5
Originally Posted by slybunda
My guess is bigger engines dont see such big differences in oil grades but small engines do.
That would be my guess too.
Just about any engine I've owned over the years, experienced 'more freedom", when thinning the oil viscosity index. But it doesn't guarantee that it's best for the engine. Sometimes what we feel in the drivers seat, doesn't correspond with what's taking place inside the engine. One time I switched to a thin-side 5w20 in my former 1999 S-10 with high-output 4.3 engine, well when I changed the oil after that 5w20 run, my magnetic oil pan bolt had a million little silvery shreds attached to it. Immediately went back to a thicker 5W30 and no more shredding occurred. But boy-oh'-boy, was it ever more responsive and peppy using the thin 5w20. I sure missed that afterwards.
 
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Originally Posted by RDY4WAR
One application I know doesn't like thick oil, particularly on in cold weather, is older Ford small blocks. A lot of people would put SAE 40 or 50 in it, it would be 30*F outside, and they'd go start it up, immediately run the dog out of it, and then have no oil pressure because they snapped the oil pump drive. The OEM pump drive in those cars is notoriously weak. Every SBF I've put together, I've put an ARP pump drive in it, even if it was just a stock rebuild.
That isn't an oil viscosity issue. That is a failure to choose the appropriate viscosity for the expected temperature range. That's why all the manufacturer oil charts have Temperature ranges.
 
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Originally Posted by mpack88
I had a dodge aries wipe out its rod bearings and oil pump due to me using valvoline 20w50 and a 20°f. It can happen.
But ... that was a Dodge Aries ... it was inevitable grin2
 
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Originally Posted by mpack88
I had a dodge aries wipe out its rod bearings and oil pump due to me using valvoline 20w50 and a 20°f. It can happen.
At 20°F it wasn't due to the grade, nor was it due to the manufacturer of the oil.
 
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How much thick or heavier from 5w20 to 5w30? I cant imagine you guys would feel a difference. I figure going from 5w to a 10w, is where you would feel a difference. How about going from 0w16 to a 0w20? Mobil 1 Afe to Ep.
 
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Originally Posted by painfx
How much thick or heavier from 5w20 to 5w30? I cant imagine you guys would feel a difference. I figure going from 5w to a 10w, is where you would feel a difference.
What do you mean?
 
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The 5 vs 10w will only be noticeable when the engine is cold. Once warmed up you won't feel a difference because they are the same grade at temperature. A 5w20 vs a 5w30 or 5w40 you could potentially feel a difference when warm but probably not when cold.
 
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Originally Posted by caprice_2nv
The 5 vs 10w will only be noticeable when the engine is cold. Once warmed up you won't feel a difference because they are the same grade at temperature.
And only around 0F or below.
 
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Originally Posted by kschachn
Originally Posted by painfx
How much thick or heavier from 5w20 to 5w30? I cant imagine you guys would feel a difference. I figure going from 5w to a 10w, is where you would feel a difference.
What do you mean?
How much of a difference would you feel going from 5w20 to a 5w30?
 
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Originally Posted by caprice_2nv
The 5 vs 10w will only be noticeable when the engine is cold. Once warmed up you won't feel a difference because they are the same grade at temperature. A 5w20 vs a 5w30 or 5w40 you could potentially feel a difference when warm but probably not when cold.
I am confused. My friend has a 03 lexus es330. He went from 5w30 to a 10w30 in the summer. He told me the car feels heavier at the throttle. He then switched back to 5w30, he said the engine felt much lighter at throttle. I told him to just stick with 5w30 as 10w is unneccessary for just local driving. Temperatures are under 90F.
 
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