Originally Posted By: Jetronic
Originally Posted By: NJ_Car_Owner
Originally Posted By: Jetronic
Originally Posted By: NJ_Car_Owner
I had the chance to look at the manual for my 2004 Hyundai Sonata and it says to use 10w30. Someone in the other thread I started suggested that I should use 5W30 vs 10W30.
IN the manual it shows that the 5W goes to a lower temp than the 10W - it makes sense and understand this. But it showed the 30 part going to higher temps in the 10W than the 5W.
I thought the 30 part would be the same (assuming all things being equal). Or is it because at 5W you're starting out at a thinner oil and the modifiers can't handle the heat?
I've seen charts like this before but always used the recommended oil so never paid attention to it.
Thanks!
Those temp range vs viscosity charts haven't been updated since they were conceived. A 5W30 contains more VI improvers than a 10W30 and a thinner base oil. Since those oils were prone to shearing permanently you'd end up with a too thin oil before the oci is up when using 5W30. It shouldn't be a problem anymore, except some oil grades are shearing on purpose.
What you need to take away is that you need enough viscosity at high temps and high shear, called HTHS viscosity.
Is this HTHS number the cSt number at 100 C? Or is this number usually not easily found? Specifically speaking the oil that was put in was Motorcraft 10W30 and since I don't change my own oil and trying to use the Ford quick lane the oil being recommended is the Motorcraft 5W30. On Ford's website there is 0.4 cSt difference with 5W30 being higher at 10.8. I am proabably looking at the wrong number that that is the highest temp they are showing. Of course I can be overthinging it as well!
What's also interesting is that the CP at -30 C is higher on the 5W vs the 10W ... again probably overthinking it.
No it's not the Cst at 100°C, and sadly you can't even deduct the HTHS viscosity from that for a multigrade oil. At least not with any accuracy but it's likely 10 cSt oil will be thinner than 12cSt oil. You'll have to find the HTHS viscosity on product data sheets, but not nearly all brands disclose these for all products. The Cst viscosity is of an oil that isn't stressed, they just measure how long it takes to drain through a hole. High shear viscosity is for an oil being worked between 2 sliding surfaces. Typically measured at 150°C as that is how hot the oil gets inside main and big end bearings during normal operation.
Luckily there are usually some good clues to what the HTHS viscosity range will be from the certifications the oil carries: ACEA ratings are divided into hths viscosity ranges and Sulphated ash ratings. Ilsac rated oils tend to sit around 3.0 cP, just above the minimum required by the SAE viscosity ratings.
How cold does it get where your car stays? 10W30 is likely just perfect for you unless the temps drop below -25°C
It was suggested to use 5W30 only because the Ford Quick Lane dealer charged me an extra $10 for using "non standard Ford oil" . I have used Jiffy Lube in the past but decided to try the Quick Lane to see how it was compared to Jiffy Lube so when it comes time for our new to us car oil changes I know if I should go there. I was surprised that they charged me the extra $10 and someone suggested getting 5W30 which is standard Ford oil; living in Jersey I see very little 0 F or 100 F days.
I was asking this question because I saw the diagram in the manual, the car doesn't get driven much these days but the oil still needs to be changed every so often and saving $10 could be a good thing assuming I'm not causing damage to the engine. Although at 13 YO (but only about 75,000 miles) I wonder how much longer it'll be around. It was supposed to be our "trade in" car but my wife's car needed a rear seal which was going to be expensive so that got traded in instead. I am wondering if the rear seal went because of maybe inferior oil as the car only had 111,000 miles on it, another reason to try Quick Lane vs Jiffy Lube.
Thanks to everyone who answered!
