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Discussion Starter #1
Was just wondering if using 10w30 Mobil 1 in the summer months (South La) would be ok?
 

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Discussion Starter #3
Why would you do that?

You have it already or something? There isn't an advantage that I can think of.
I could be completely wrong about this (yes i put it in yesterday)but I thought it may help with this very small oil leak I have. It never drops to the ground....ever, but leaks over my starter and the surrounding area. Plus the fact that it's so hot already and that when at operating temp it's still 30 weight, i figured the little bit thicker oil might quieten down my old motor a bit and possibly stop the leak.
 

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Discussion Starter #5
Have you tried something like this :

https://mobiloil.com/en/motor-oils/mobil-1/mobil-1-high-mileage

in the proper weight?

I doubt you'll hurt anything, IIRC the 05-07 engines called for 5w30 and they switched to 5w20 to save a small bit of gas mileage in the later model years.
My apologies, I should've mentioned that I have been using the HM Mobil 1 5w30 since about 80k. I'm right at 100k now. I may get a torque wrench and go over all of the valve cover bolts. I should have thought to do that before the heavier oil I suppose.
 

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Discussion Starter #6
Does anyone think I'll actually HURT anything with the 10w30 during the summer or should I drain the brand new 10w30?
 

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My apologies, I should've mentioned that I have been using the HM Mobil 1 5w30 since about 80k. I'm right at 100k now. I may get a torque wrench and go over all of the valve cover bolts. I should have thought to do that before the heavier oil I suppose.
Yeah, I wouldn't personally go to a heavier oil to fix a leak. I am @ 105k with no leaks.

Honestly 10w30 should be fine in the summer, or in the winter in LA.
 

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The 10w30 is not actually heavier weight oil than the 5W30. The frst number before the W indicates the weight of the oil when it is cold to indicate flowability in really cold temperatures. The second number (30 in this case) indicates weight when the oil is warm or hot. In this case the oil is the same weight when hot so there is no difference in weight between 5W30 and 10W30 when the oil is hot.

You are just fine with the 10W30 - you won't hurt a thing. I doubt that changing oil will help with the oil drip however.

Dan
 

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The 10w30 is not actually heavier weight oil than the 5W30. The frst number before the W indicates the weight of the oil when it is cold to indicate flowability in really cold temperatures. The second number (30 in this case) indicates weight when the oil is warm or hot. In this case the oil is the same weight when hot so there is no difference in weight between 5W30 and 10W30 when the oil is hot.

You are just fine with the 10W30 - you won't hurt a thing. I doubt that changing oil will help with the oil drip however.

Dan
True on both accounts.
 

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Discussion Starter #10
Thanks guys. I appreciate the feedback. I'll try and re torque those valve cover bolts and see what happens. I have right at 100k and they might have backed off a teeny bit. If not, I'll just deal with it. The leak is so minor it doesn't really even appear to show on the dipstick until around 3k miles and then it takes less that a fourth of a quart to top it off. I already have the new gaskets in case it worsens but right now the juice isn't worth the squeeze, lol.
Thanks.
 

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You need an oil pressure gauge to see what the different weight is actually doing in the motor.

Switching to a thicker oil to slow a leak is a band aid at best and you're risking poorer lubrication of the motor to slow a slight leak. Replacing the seal is the best way to fix the leak, I know that is easier said than done.

As well, since synthetic flows better, especially through small openings compared to conventional oil, switching to synthetic is more likely to flow more oil through slight leaks.

Since its very warm in summer in Southern Louisiana, and high temps require higher viscosity oils, that is some offset, i.e. better than someone that using a higher oil viscosity where the summers are very cool.

Oh, BTW, oil viscosities are NOT that neat and clean or digital switch over to state that 5W30 and 10W30 are the same viscosity when warm. The viscosity change is a curve, so even if the viscosity numbering was perfect 10W30 would start off at higher viscosity and stay higher than 5W30 until the oil got to 100°C, then they would meet to be the same viscosity. But the viscosity number are NOT perfect and the real viscosities are just close to the numbers and you often find 10W30 is a little thicker at all temps, except at the extremes (way above/below freezing/boiling of water).

Regardless, 5w30 and 10W30, are close enough that I'm really splitting hairs, it's NOT like using one or the other would do any damage to a motor that specified one or the other. I'm just sayin, 5w30 and 10w30 are NOT the same viscosity other than at 0°C, they are a different viscosity for every temp except 100°C. But they are close and close enough that someone doesn't have to freak out.

Honestly, we just don't know if 10W30 in your 4.7L is ok or NOT, if you had an oil pressure gauge, that would help. I'd agree, its NOT likely to cause a problem, but we can't guarantee it.

Since synthetic oil flows better than conventional oil (yea, I know viscosity "a" measure of how well a fluid flows, its a complicated measurement) the fact your using synthetic in a higher weight offsets, makes it a little less bad, your using a thicker than recommended viscosity.
 

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Discussion Starter #13
You need an oil pressure gauge to see what the different weight is actually doing in the motor.

Switching to a thicker oil to slow a leak is a band aid at best and you're risking poorer lubrication of the motor to slow a slight leak. Replacing the seal is the best way to fix the leak, I know that is easier said than done.

As well, since synthetic flows better, especially through small openings compared to conventional oil, switching to synthetic is more likely to flow more oil through slight leaks.

Since its very warm in summer in Southern Louisiana, and high temps require higher viscosity oils, that is some offset, i.e. better than someone that using a higher oil viscosity where the summers are very cool.

Oh, BTW, oil viscosities are NOT that neat and clean or digital switch over to state that 5W30 and 10W30 are the same viscosity when warm. The viscosity change is a curve, so even if the viscosity numbering was perfect 10W30 would start off at higher viscosity and stay higher than 5W30 until the oil got to 100°C, then they would meet to be the same viscosity. But the viscosity number are NOT perfect and the real viscosities are just close to the numbers and you often find 10W30 is a little thicker at all temps, except at the extremes (way above/below freezing/boiling of water).

Regardless, 5w30 and 10W30, are close enough that I'm really splitting hairs, it's NOT like using one or the other would do any damage to a motor that specified one or the other. I'm just sayin, 5w30 and 10w30 are NOT the same viscosity other than at 0°C, they are a different viscosity for every temp except 100°C. But they are close and close enough that someone doesn't have to freak out.

Honestly, we just don't know if 10W30 in your 4.7L is ok or NOT, if you had an oil pressure gauge, that would help. I'd agree, its NOT likely to cause a problem, but we can't guarantee it.

Since synthetic oil flows better than conventional oil (yea, I know viscosity "a" measure of how well a fluid flows, its a complicated measurement) the fact your using synthetic in a higher weight offsets, makes it a little less bad, your using a thicker than recommended viscosity.
Again, thanks very much for the super-informative reply. I'll prob just leave it in the until August passes then switch it out no matter the mileage I've put on it. Thanks again.
In a side note, I've read lots of your posts and they all are very informative. Thanks for that. Reminds me of Robby's posts. Speaking of.....I don't remember seeing any new posts from him in quite some time.....he still around the boards?
 

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You need an oil pressure gauge to see what the different weight is actually doing in the motor.

Switching to a thicker oil to slow a leak is a band aid at best and you're risking poorer lubrication of the motor to slow a slight leak. Replacing the seal is the best way to fix the leak, I know that is easier said than done.

As well, since synthetic flows better, especially through small openings compared to conventional oil, switching to synthetic is more likely to flow more oil through slight leaks.

Since its very warm in summer in Southern Louisiana, and high temps require higher viscosity oils, that is some offset, i.e. better than someone that using a higher oil viscosity where the summers are very cool.


Oh, BTW, oil viscosities are NOT that neat and clean or digital switch over to state that 5W30 and 10W30 are the same viscosity when warm. The viscosity change is a curve, so even if the viscosity numbering was perfect 10W30 would start off at higher viscosity and stay higher than 5W30 until the oil got to 100°C, then they would meet to be the same viscosity. But the viscosity number are NOT perfect and the real viscosities are just close to the numbers and you often find 10W30 is a little thicker at all temps, except at the extremes (way above/below freezing/boiling of water).

Regardless, 5w30 and 10W30, are close enough that I'm really splitting hairs, it's NOT like using one or the other would do any damage to a motor that specified one or the other. I'm just sayin, 5w30 and 10w30 are NOT the same viscosity other than at 0°C, they are a different viscosity for every temp except 100°C. But they are close and close enough that someone doesn't have to freak out.

Honestly, we just don't know if 10W30 in your 4.7L is ok or NOT, if you had an oil pressure gauge, that would help. I'd agree, its NOT likely to cause a problem, but we can't guarantee it.

Since synthetic oil flows better than conventional oil (yea, I know viscosity "a" measure of how well a fluid flows, its a complicated measurement) the fact your using synthetic in a higher weight offsets, makes it a little less bad, your using a thicker than recommended viscosity.
The viscosity modifiers do not function in a linear fashion as temperatures rise. The very fact that a 10W30 and 5W30 have the same viscosity index at 212 deg. F proves this. What you are saying is not correct. Also a synthetic oil and a petroleum based oil of the same weight will flow through an orifice of the same size at the same rate.

When the first synthetic oils were developed the molecular makeup would allow the oil to seep through very small spaces and these oils had to be sold in metal cans to prevent leakage. Modern synthetic base stocks do not do this.

My son is a chemical engineer and we have discussed these things quite a bit.
 

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The viscosity modifiers do not function in a linear fashion as temperatures rise. The very fact that a 10W30 and 5W30 have the same viscosity index at 212 deg. F proves this. What you are saying is not correct. Also a synthetic oil and a petroleum based oil of the same weight will flow through an orifice of the same size at the same rate.
Umm, I said it was none linear?
The fact that 10W30 and 5W30 have the same viscosity at 100°C or 212°F only proves they have the same viscosity at the same point water boils.
The very fact that 10W30 and 5W30 have a different viscosity at 0°C or 32°F only proves they do NOT have the same viscosity for all temperatures.
What viscosity does each have at 50°C or 122°F?
What viscosity does each have at 125°C or 257°F?
So what exactly did I say that was incorrect? Cause everything you've said has NOT contradicted anything I said?

Synthetic oil has molecules of uniform size, while conventional oil has molecules of varying size. So when you force Synthetic oil through an orifice you get a simple measure of the viscosity and since the molecules are uniform size there is very little variance. When you force conventional oil through an orifice, you get an average again, but the variance of that average is much larger, cause the molecules vary in size. When you force these fluids through something far more complex and far longer than a simple orifice, NOT to mention pump dynamics and filtering, the variances to the average can have a much bigger effect. That is how you can have the same viscosity, but one flows "better" than the others, the one being more uniform having less trouble and problems, and thus staying closer to the average than the other, that is less uniform having more trouble and problems, and thus varying farther away from the average.

BTW, since most off the shelf synthetics are group III oils, meaning hydro-cracked oil, i.e. ultra refined and arguably put through a synthesizing process, they are petroleum based oil.

BTW, the "W" in the mulit-viscosity label means Winter, and there is a separate test for flow, where the oil is poured on an inclined flat plate at a certain temperature and timed for how long before it will flow off the plate. If the test of forcing the oil through and orifice is the whole story on flow characteristics, why would they have this separate and very different "W"/Winter test for flow?
When the first synthetic oils were developed the molecular makeup would allow the oil to seep through very small spaces and these oils had to be sold in metal cans to prevent leakage. Modern synthetic base stocks do not do this.

My son is a chemical engineer and we have discussed these things quite a bit.
Yes, synthetic and conventional oil has been improved vastly over the years. But the conventional wisdom still stands that synthetic will pass through leaks more readily than conventional oil. Likely the reason is the uniform molecule size, while conventional molecule size varies, logically there is a greater opportunity for the larger than average molecules in conventional to hang up, slow and build up and slow the leak, while the synthetic molecules will be the same size and keep flowing the same rate.

No two leaks are the same, and it is often recommended to try and see the results, sometimes synthetic does NOT make an appreciable difference in a leak, sometimes it does.

People also have experience an increase in oil pressure when switching to synthetic of the same viscosity? Personally I have observed this in older engines. So, how does a synthetic and conventional oil of the same viscosity produce different oil pressures under the same conditions? Could there be more to fluid flow and viscosity than forcing it through an orifice?
 

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Like I said, the difference between 5W30 and 10W30 is so little it should NOT be of concern, but the point I was trying to make the two different oils start at different points but end at the same point. So, as the oil warms, the difference in viscosity will close till they reach the end point. And yes, it is NOT linear, its a curve (that means non-linear), but the curves will follow each other usually but NOT always, so the 10W30 will always be higher than the 5W30 until the curves touch when they reach the end point.

Notice they don't sell 6W30 or 9W32 or 0W19 or 4W21, the real viscosities often do NOT fall right on the 5 weight increments they label the oil, the actual weights will vary slightly, but will be very close to the weight they label it at. So, it is possible that even though the label on the bottle would indicate at 100°C, 5W30 and 10W30 would be the same viscosity. But look at the chart below, the curves don't touch at 212°F, they are close but don't actually touch.

So which oil is thicker? Again, note how close they are, so like I said there is no reason to freak out about the difference in 5W30 and 10W30, and it is an academic point only, but 10W30 is thicker than 5W30 up to 212°F/100°C, same for 10W40 vs 5W40 and 5W20 vs 0W20 (in this case the lines are so close they seem to be touching the entire time). And in some cases they don't even touch at the higher temp, the label the bottles is in increments of 5 weight, the oil can vary a bit from that, but it will be very close, but that explains why the viscosity curves don't touch despite the label indicates they should.
 

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And one more point, since we are going so in depth about oil. The closer the cold/hot viscosity on multi-viscosity oils, usually the better. They use different weight base stocks and less additives/viscosity modifiers, so the oil with the narrower viscosity spread will usually be a slightly better oil or at least NOT vary in viscosity as much.

Look in the Owners Manuals that recommend 5W30 or 10W30, since the Commander's O.M. will just recommend 5W20, look at the chart below, it will be similar to charts you'll find in other O.M.

Also look at the chart above, note how close the viscosities are for 5W30 and 10W30. Why would operating at extremes call for a tiny difference in viscosity that 5W30 or 10W30 would provide you? Well, two reasons:
1.) The chart above doesn't go to the extremes that the oil would experience in the conditions below, so often you'll see the lines for 5W30 and 10W30 will start to separate a lot more if the chart above went out to those extremes.
2.) The hotter condition for the engine will be murder on the oil, the narrower viscosity range of the 10W30, for the reasons I've already mentioned and probably more, will help the oil stand up to the torture of those conditions better than a 5W30. Same for 5W30 in extreme sub zero temps, the viscosity lines probably separate even more, and you need the thinner 5W30 in those extremes cold temps, so it is thin enough to flow properly starting and warming up the motor in those extreme colds.
 

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...So what exactly did I say that was incorrect? Cause everything you've said has NOT contradicted anything I said?...
I love cut and paste LOL
That's NOT an answer.

If you believe I cut and pasted those posts, you just have to copy and paste the text into Google and it will provide you the source that I cut and pasted it from, and show everyone.

Good Luck, I don't think you'll have any luck backing up your insinuation because I composed the posts from scratch, the graphics to help illustrate the points, were copy and pasted from Google Image searches that took only a few seconds of searching.
 
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