Please shoot holes in this argument.

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114
Location
Colorado Springs
Just wondering what might be wrong with this argument: Since motor oils in the past could have up to a 375% increase in viscosity and still met SAE grades, why would one have any concerns with using Mobil 0W-40,for example, that stays in grade for at least 3k-5k+ miles? The percentage increase in viscosity from a mid range 30w to a mid-range 40 ( 11 to 14) is only around 30%. An order of magnitude less than 375%. The point being, the viscosity increase of the 40 weight oil is nothing compared to the SAE sequence test increase of 375%, so why worry about. The engine would hardly noticed the increase, but the protection would be greater. So it seems that we should take advantage of the new generation oils like Mobil1 0W-40 and get the cold, start-up protection along with a HTHS of 3.6/14.3 viscosity at operating temperatures for protection. Forget about CAFE, of course. Let me know what I am overlooking? Thanks
 
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5,785
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Dixie
The analogy you made to the API sequence IIIF test is not really valid. These are designed to be severe overtests and the allowable test limits aren't what you'd want to use for an actual application. If the oil thickens by 375%, that means it's almost five times as thick as it started out. In other words, you basically have a semi-fluid grease in the crankcase at that point which would quickly ruin the engine from overheating. For a really long change interval of > 20,000 miles, I expect the oil to thicken by 20%-25%, but that would be the limit of what I'd consider acceptable. The reason why so many of the very long drain oils in Europe - like the Castrol SLX - are 0w-30 grades is that they expect them to thicken to a 40wt over time. TooSlick
 

J

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434
Location
Berkeley
quote:
Originally posted by Fillherup: So it seems that we should take advantage of the new generation oils like Mobil1 0W-40 and get the cold, start-up protection along with a HTHS of 3.6/14.3 viscosity at operating temperatures for protection. Forget about CAFE, of course. Let me know what I am overlooking? Thanks
Hi, Clavinism alert! [Smile] First of all, Mobil 1 0W-40 is an excellent oil. What other ACEA A3/B3 oil can you buy for less than $5 USD a quart anywhere ? Do you really need 0W? If not, Delvac 1 may be a better oil for you. The only down-side is that Delvac 1 has no Moly. [Cheers!] Jae
 
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5,785
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Dixie
j, Castrol Syntec 10w-40 at Walmart is also ACEA, A3/B3 rated for about $4.25/qt ....Not that I'd ever buy the stuff [Wink] FWIW, I think a properly formulated, 15w-40, group II basestock oil could pass ACEA "A3/B3", so it's not the Holy Grail of lubrication science. Some of the OEM European specs are quite a bit tougher to pass, like VW 502, BMW Longlife, DB 229.3, etc. So you want to look for those as well .... Ted
 

Fillherup

Thread starter
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114
Location
Colorado Springs
TooSlick, I guess the real issue is that 40 weight oils, like Mobil1, are really safe today because they thicken so little vs dino oils of yesterday. So using them instead of thin 30 weight oils is not really an issue anymore. Is this a valid conclusion? BTW, what what the purpose of the sequence test at 375%? It seems that 375% does make no sense, when you think about it. Why not stop the test at some lower value? [ April 24, 2003, 02:22 AM: Message edited by: Fillherup ]
 
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5,785
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Dixie
Fillerup, The Mobil 1, 0w-40 has the same HT/HS viscosity as the xw-30 Amsoil synthetics, so I really just consider it to be a thick 30wt oil in that respect. It's really fine to use, I was just giving you a hard time [Smile] The Sequence IIIF test that's part of the SL specification calls for running a 3.8L, GM V-6 engine @ 3600 rpms, with a rated load of 100 bhp and the oil temp stabilized @ 155C/311F. They run the test for 80 hours at what amounts to an equivalent road speed of 100+ mph. Quite honestly, if they didn't set very lax test limits you could never get a petroleum oil to pass any of these tests. That would be fine by me of course, but the API would have a fit ... [Wink] TS
 
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1,432
Location
Virginia
Good morning; At the risk of REALLY "Clavining" you, I have an interesting flyer (from the 76 oil co) stating that the new sequence IIIF test (which coincides with the SL spec) allows only 275% at 80 hours vice 375% at 64 hours. If so, that's another indicator that the SL standard was more than a rubber stamp! [Off Topic!] As far as CAFE goes, I think it's silly that companies are trying to increase their CAFE by decimal points through the use of different oils (ie Ford, Honda). If they really wanted to make a fuel economy difference, they ought to just give people a free tire gauge with their new car purchase. And then Congress could pass laws making it OK for ordinary citizens to give people a free dope slap if their tires are low! [Duh!]
 
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951
Location
Loveland, Colorado
quote:
Originally posted by Matt89: As far as CAFE goes, I think it's silly that companies are trying to increase their CAFE by decimal points through the use of different oils (ie Ford, Honda). If they really wanted to make a fuel economy difference, they ought to just give people a free tire gauge with their new car purchase. And then Congress could pass laws making it OK for ordinary citizens to give people a free dope slap if their tires are low!
I like this!! Matt89 for Congress!!
quote:
Originally posted by Fillherup: I guess the real issue is that 40 weight oils, like Mobil1, are really safe today because they thicken so little vs dino oils of yesterday. So using them instead of thin 30 weight oils is not really an issue anymore. Is this a valid conclusion?
I agree completely. I think we have a skewed view of an oil's ability because we scrutinize everything here. (It can't be that we're all this anal, can it?) (Hey wait, should this go into the "slogans" thread?) If 3k miles was OK on an API SF petroleum oil, why are we worried about 10k miles on an SL, ACEA A3 oil?? (I'm not worried of course; but then I'm not the best example to follow, either...) [Edit: boneheaded forgetfullness.] [ April 24, 2003, 11:43 AM: Message edited by: Greg Netzner ]
 
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605
Location
Mississauga, Ontario
Fyi, I've been using M1 0w40 for the past 3,000km. M1 5w/10w-30 before. No change in fuel economy what so ever. It's actually a little better since the weather warmed up and I switched to Esso Supreme92. CAFE who? [Roll Eyes] [Smile]
 
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