Oil consumption and it's relation to HTHS/cst@100degC?

[Quick_lude]

This is related to the M1 0w40 and how stable it is thread. As some of you know I have a 2000 Prelude with the H22a engine that starts to use oil at about 4,000km into the interval. Until 4,000km it will use maybe .25L if any. After 4,000km it will use about 1L/1000 miles. I always used M1 5w30. Used 10w30 on the last interval, same results. My question is this: is this consumption caused by the oil thinning out during use? Is the problem the 3.0 HTHS number of the oil or the fact that M1 is on the "thinner" side of 30w? Are the HTHS and weight related? I am going to experiment with the M1 0w40 for this interval and see how it holds up after 4,000km with the 3.6 HTHS and 14.4 cSt. If my theory is correct I should see reduced usage if any. What do you guys think?

 

[Patman]

HTHS is somewhat related to viscosity, yes. But, if you have two different brands of oil, both at 10.0cst, they could have different HTHS numbers though, depending on how they are created. But with the same oil, as it thins out, it's HTHS will indeed drop. So that's a good part of the reason why you see more consumption as your oil wears out. You should see a pretty good improvement with the 0w40. When are you putting it in?

 

[Quick_lude]

As soon as it gets a little warmer.. Don't have a garage. That was my next question, what about a 30 weight oil with a higher HTHS number? Would it resist burning better than say a 40 weight oil but with the same or lower HTHS number? For example the Amsoil 10w30 has an HTHS of >3.5 which is essentially the same as the M1 0w40 but the cSt is only 11.90 vs 14.4. Would the M1 resist usage better because it's a 40w? What about the noack volatility, how does that value affect my scenario?

 

[Ken2]

Schaeffer #703 10W-30 has an HTHS viscosity of 3.5. I don't know the exact 100° vis. Patman probably has some of this he's using as doorstops that he'd sell you just to clean out his storage room. It would be, what?, just over half the cost of Amsoil with about the same life and same protection? Ken

 

[mdv]

quote:

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Originally posted by Quick_lude: For example the Amsoil 10w30 has an HTHS of >3.5 which is essentially the same as the M1 0w40 but the cSt is only 11.90 vs 14.4. Would the M1 resist usage better because it's a 40w? What about the noack volatility, how does that value affect my scenario?

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I don't know if NOACK, HT/HS numbers or just different formulations that caused this, but I know of one guy with a 97 Prelude who's oil consumption was cut in half when he went from Mobil 1 15W-50 to Amsoil's 10W-40.

 

[Patman]

quote:

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Originally posted by Ken2: Schaeffer #703 10W-30 has an HTHS viscosity of 3.5. I don't know the exact 100° vis.

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The thing that has me curious is that Schaeffer advertises their 10w30 #703 as having a viscosity of between 10-12cst. I've seen some UOAs where it's close to 12 and my own have been closer to 10. So I wonder if the 3.5 HTHS is based on a batch with a viscosity of 12? It'll be interesting to see where my viscosity is on my next interval (the one beginning in April that is), since I bought this case of 10w30 from a different distributor in a different province, so it's a totally different batch.

 

[buster]

This is a great question. I find it interesting that your oil consumption doesn't occur until a certain amount of miles are put on the oil. If it is bc of thinning, I'd be disappointed with the oil. Which lead me to ask, is thinning out a bad thing? I don't recall ever coming up with an answer for this. You would think Mobil 1 is aware of there oil thinning out. And what about Vettes and other cars that call for 10k mile plus drains using M1 5w-30? 20wts are fairly new to the market and Mobil has always formulated there oil on the light side for MPG, I assume. This could also be a reason they don't call for extended drains?? [ February 28, 2003, 06:15 PM: Message edited by: buster ]

 

[Patman]

quote:

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Originally posted by buster: This is a great question. I find it interesting that your oil consumption doesn't occur until a certain amount of miles are put on the oil. If it is bc of thinning, I'd be disappointed with the oil. Which lead me to ask, is thinning out a bad thing?

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In theory yes, because thinning out means the VI improvers are breaking down, and when they do, they become "useless sludge molecules". (I love that term) Plus if it thins down too far, you'll end up with more engine wear due to having too little protection. I'm personally not comfortable at all if an oil thins out by more than 1 cst.

 

[buster]

So patman, would you say then that Mobil 1's main weakness or flaw is the thinning out? I did decide to go back to M1, for availability reasons, but I don't like the fact that it thins out. I know SS isn't supposed to thin out as much, but it still seems to have this problem ocasionaly. Mobil's cSt's are too low IMO. [ February 28, 2003, 09:21 PM: Message edited by: buster ]

 

[Patman]

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Originally posted by buster: So patman, would you say then that Mobil 1's main weakness or flaw is the thinning out? I did decide to go back to M1, for availability reasons, but I don't like the fact that it thins out. I know SS isn't supposed to thin out as much, but it still seems to have this problem ocasionaly. Mobil's cSt's are too low IMO.

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M1 5w30 and 10w30 don't thin out, although I do find them a bit too thin to start out with anyways. M1 is a very good oil, which shows good UOAs on here, but it does have it's limitations. It's lower HTHS makes it less desirable for harder driving, IMO.

 

[Quick_lude]

quote:

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Originally posted by Patman:

quote:

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Originally posted by buster: So patman, would you say then that Mobil 1's main weakness or flaw is the thinning out? I did decide to go back to M1, for availability reasons, but I don't like the fact that it thins out. I know SS isn't supposed to thin out as much, but it still seems to have this problem ocasionaly. Mobil's cSt's are too low IMO.

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M1 5w30 and 10w30 don't thin out, although I do find them a bit too thin to start out with anyways. M1 is a very good oil, which shows good UOAs on here, but it does have it's limitations. It's lower HTHS makes it less desirable for harder driving, IMO.

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Personally I think the old TriSyn did thin out, especially in my engine. At least that is my theory.. I'll probably use this next batch of 0w40 for about 5K miles since I drive the car very hard in the summer, auto-x and track lapping days where the engine is always at 5200-7500rpm in VTEC mode. If I don't burn any or as much oil after 3,000 miles the higher HTHS and cSt@100C will be the only reason for that. If nothing will change then I will be really stumped..

 

[Patman]

quote:

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Originally posted by Patman: The thing that has me curious is that Schaeffer advertises their 10w30 #703 as having a viscosity of between 10-12cst. I've seen some UOAs where it's close to 12 and my own have been closer to 10. So I wonder if the 3.5 HTHS is based on a batch with a viscosity of 12?

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I thought I'd bring this one back up since the question wasn't answered before and I'm really curious about it.

 

[Dr. T]

I'll just say that it <i>may</i> have an effect when comparing the same brand...otherwise, my consumption has gone down 80% since switching from M-1 15-50 to Syntec 5-50.

 

[buster]

Good question. I think there is a way to compute it..I remember TS doing it. My opinion would be the 3.5 HT/HS is based on the 12. The reason I think this is if you look at Amsoil's Kvisc@100C, they all are in the upper 11's cSt and they all have 3.5 HT/HS on average. Mobil 1 being a light 30wt. as we all know, @ 9.8cSt are barely 3.0/3.2 (0w-40 is 3.6). Hey, Schaeffer's has a higher HT/HS then M1. M1 is really formulated for fuel efficiency. Does a great job considering though. To the top question, I think Mobil's consumption issues are the lightness of the oil and NOAK volatility/volatility of VI's. I think the VI's are volatile, especially in the 0w-30. I found the 10w-30 to be the best for consumption. 0w-40 was decent. Amsoil 0w-30 has been the best oil for consumption that I have used.

 

[TooSlick]

QuickLude, All things being equal, a thicker oil will generally reduce oil consumption, particularly in a high mileage engine. For oils of the same SAE grade, I have found that Noack volatility is a better way to predict oil consumption in actual service. In this test, the oil is heated up to 250C in order to accelerate the evaporation rate. It is held at this temp for 1 hr while a slight vacuum is pulled to draw off the oil vapors. Noack volatility is a function of both the base oils used and the particular additive chemistry. Noack volatility of the Amsoil 10w-30 is 5.5%, based on some very recent testing, and HT/HS is 3.5-3.6. I believe you will see lower oil consumption with this oil than with the Amsoil 0w-40. The wide range synthetics like 0w-40 and 5w-50 tend to have the highest evaporation rates and a 10w-30 is going to be more shear stable. The Redline synthetics also have very low evaporation rates, so if you can find some of that at a decent price I'd try their 10w-30. TooSlick

 

[Quick_lude]

Thanks Slick, since I started my M1 0w40 experiment I'm using about .25L/1000km. Not bad, but not that good either.. I have been using VTEC a lot more though to test out the oil and for some fun since the weather finally became warm. If I'm still consuming with an exponential curve deeper into the interval I'm going to try the Amsoil 10w40. It's Noack numbers are better than the M1 0w40. We'll see if it makes a difference in my engine.