Some thoughts on manufacturers suggested viscosities....

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412
Location
Slinger, Wisconsin
I sent an private message to a fellow member on www.honda-tech.com and this was our discussion. His post that caught my eye was this. " Using 10W30 when outside temperatures are below 20 degrees F is not recommended, according to the owner's manual. And, as noted above, 5W30 is preferred at all temperatures. Am I the only one who has ever opened his owner's manual? [Razz] " BrewCityR (10:07 PM 3/10/2003): I no doubt agree with those 10w30 recommendations. I think with a good synthetic or syn blend (Schaeffer) 10w30 is fine for 0,5,10 degree Farenheit startups. Granted, I may buy a case of 5w30 Schaeffer for my daily driver next fall/winter to use. py1091 (10:09 PM 3/10/2003): The owner's manual has the Acura name on it. It was written by the engineers who designed the car, including the engine. BrewCityR (10:12 PM 3/10/2003): So you wouldnt agree that the cold pumpability properties differ from dino to semi-synthetics to synthetics? py1091 (10:17 PM 3/10/2003): I think your logic is convoluted if you think that you can use a viscosity that is NOT recommended in the owner's manual but you are trying to justify it because it's synthetic instead of conventional oil. And you are definitely DISOBEYING the advice in the owner's manual, which states, "You may use a synthetic motor oil if it meets the same requirements given for conventional motor oil: energy conserving, a service classification of SJ, and the proper weight as shown in the chart". Furthermore, if your car is under warranty, using the wrong viscosity of oil gives them a basis for denying warranty claims if anything goes wrong with your engine. BrewCityR (10:19 PM 3/10/2003): LMAO. Don't disobey the owner's manual as you might get sent to your room. Thoughts, comments? Just wanted some feedback.
 

JHZR2

Staff member
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45,653
Location
New Jersey
I stumbled on this at a saab site that I went to by accident... I think it is good advice: http://www.saabspokane.com/Jan_2001.htm Synthetic Oils work well in winter. For the longest engine life, always use the highest grade of oil that will work for the temperature range of the season. Too low of viscosity improves starting, but does not cushion engine bearings adequately. Older engines with ‘worn in tolerances’ will not build an adequate hydrodynamic wedge above the bearings with lighter oils, and they will eventually be flattened, producing a noticeable bearing rattle. This will shorten engine life by upwards of 75,000 miles. Too high of viscosity, however, especially with mineral oils, (using a 20/50 in winter, for example) may affect starting and delays startup lubrication. We do not recommend any 5W30 or lighter Multi-grades in our Winter Climate. For summer, use 15W Multi- (15/40-15/50 etc). Unfortunately, most new manufacturers are recommending and using the 5W multi-grades. We strongly urge you to use no lighter than 10/30 oil in wintertime, and avoid 10-40’s. Because of the superior Flow Characteristics of the Mobil 1 Synthetic Oils, we are finding excellent results with a 50% blend of 10/30, and 15/50 Mobil 1 Synthetic Motor Oil. For summer, use 15/50 Synthetic. Change synthetic oil every 5000 miles; change mineral oil every 3000 miles.
 
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500
Location
Vermont
He thinks your logic is convoluted??? As opposed to his complete lack of logic, just following the manual like a good little subject. Wow, I suppose if you produced a chart that showed some (if not all) sythetics of 10W-XX have a lower pour point that most cheap 5W-XX, he'd still claim your logic was convoluted. It's funny how easily people give up their ability to think and choose and let others do the thinking for them. Actually, more scary than funny, but you get what I'm saying.
 
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342
Location
fairbanks, alaska
I have a Mazda B4000, the manual states to use 10w30 summer temps and 5w30 winter. However it is manufactured by Ford and the spec sticker under the hood states recommended weight 5w30.
 
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207
Location
The Badger State
It's my understanding that the "W" on multi-grade oils represents it's viscosity at 0F. Is this true? If this is the case, and given the fact synthetic basestock oils do not need pour point depressants added to them like petroleum basestocks do, wouldn't the issue of "W" be a moot point in regard to synthetics? It would stand to reason then, that the owner's manuals for many vehicles are using recommendations for petroleum basestock oils, and not considering synthetics at all.
 
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874
Location
Pacific NW
Rebel, the "W"inter rating is the same for conventional and synthetics. Each weight has it's own qualifying temperature and maximum friction. Synthetics may or may not need vii's, depending on the basestock quality and target viscosity. Varies by oil. Good reading at Lubrizol's site... Ratings, temps, and friction: Dec99 Qualifications General viscosity: Viscosity Your point isn't without merit though. We don't know manufacturers aren't padding their safety margin. Since they have no control over whether customers purchase $.69 or $10/qt oil they need to ensure minimum performance specs. Then we get into CAFE debates. [Smile] Back to BrewCity's situation, methinks he's found another board to educate. I don't know who these people work for but the manufacturers I've worked for don't burn engineers' time writing user manuals. [Roll Eyes] Proofing maybe, but not until marketing, legal, service, and editors turn your specifications into mishmash, and undo fixes the night before printing. Add the influences of API politics and it has to be a nightmare. David
 
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114
Location
Colorado Springs
When I do my oil checks at 0F in the freezer, even the synthetics oils are thicker than oils at engine operating temperatures. So I don't get the lack of bearing protections of 5W oils at low temps, if you are looking at viscosity for bearing protection. If anything, they would give more protection being thicker at low temps, it seems. A dino 5W give the 'protection' of STP for most oils at 0F! And at operating temps, a 0W-30, 5W-30, 10W-30 should be approximately the same vis- right? So what am I missing that makes using a 5W-30 or even a 0W-30 in winter so bad?
 
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2,480
I think the concern was using a 10-30 in the winter. The 5-30 will be obviously thinner at colder temps.. Any oil designated with a 'W'...even a 20w-50, will provide at adequate lubrication down to -15C...synthetic having better flow characteristics than conventional. It's just if your starter isn't up to the task, it will be a tough start to crank a 15-50 at these temps...not to mention the fuel consumed in warming up the oil. With fuel efficiency at the top of the list...thinner and thinner oils are being recommended in order to achieve this efficiency all the while allowing the engine to survive the warranty period.
 

Patman

Staff member
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21,990
Location
Oakville, Ontario
quote:
Originally posted by Dr. T: I think the concern was using a 10-30 in the winter. The 5-30 will be obviously thinner at colder temps.. Any oil designated with a 'W'...even a 20w-50, will provide at adequate lubrication down to -15C...
There is absolutely no way I'd ever recommend anyone put in a 20w50 oil into an overhead cam engine in the winter time. Even if it never got below -15C, you'd definitely be wearing out your engine quicker with that oil versus a 5w30 or 0w30. I think those W designations are very misleading. I don't think 20-50 oil should even be given the W designation, it's cold weather characteristics are completely terrible.
 
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2,480
Yeah, I used to think that too. But, it's right in the my non-CAFE owner's manual. I think we're just confused about oil performance...obviously an oil will not 'flow' the same at these temps as it will in the middle of summer...but, I will attest that it doesn't have to. An film thickness of oil will be present on all parts adequate enough until the oil starts pumping again...using slick 50 or not ;0 ...Else no manual would recommed these oils at low temps.
 

Patman

Staff member
Messages
21,990
Location
Oakville, Ontario
quote:
Originally posted by Dr. T: Yeah, I used to think that too. But, it's right in the my non-CAFE owner's manual. I think we're just confused about oil performance...obviously an oil will not 'flow' the same at these temps as it will in the middle of summer...but, I will attest that it doesn't have to. An film thickness of oil will be present on all parts adequate enough until the oil starts pumping again...using slick 50 or not ;0 ...Else no manual would recommed these oils at low temps.
That's just it, 99% of them DON'T recommend that thick oil in cold temps. Certainly not for a small OHC engine.
 
Messages
903
Location
CA
For my small OHC engines the manuals say 20w50 can be used from 15F and above. That's for a '88 Civic and '98 Honda bike. Same for my Suzuki.
quote:
Originally posted by Patman: [QUOTE]That's just it, 99% of them DON'T recommend that thick oil in cold temps. Certainly not for a small OHC engine.
[ March 11, 2003, 11:05 AM: Message edited by: satterfi ]
 

Patman

Staff member
Messages
21,990
Location
Oakville, Ontario
quote:
Originally posted by satterfi: For my small OHC engines the manuals say 20w50 can be used from 15F and above. That's for a '88 Civic and '98 Honda bike.
quote:
Originally posted by Patman: [QUOTE]That's just it, 99% of them DON'T recommend that thick oil in cold temps. Certainly not for a small OHC engine.

Things have changed a lot since 1988 though, my wife's 2000 Civic's manual only lists 5w30 and 10w30. Given the -21C pour point of Castrol 20w50, I would never put this in any engine of any kind in the winter, no matter what. There is no way that oil is going to flow properly even at -10c in order to give proper protection.
 

mph

Messages
356
Location
Johnstown, PA
quote:
Originally posted by BrewCityR: It was written by the engineers who designed the car, including the engine.
Then ask him why owner's manuals for the same engine in other countries specify different viscosities. Seriously, every time I read an oil thread on honda-tech.com, I want to puke. I'm half tempted to point them here, but I fear for what might happen to this board! (Actually, every time I dare to leave the Road Race/Autocross forum on honda-tech.com, I want to puke.)
 

MolaKule

Staff member
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21,725
Location
Iowegia - USA
Dr T, I think it's more than a matter of starter torque. Large Clearance engines would be able to start on 20W50 better than the more modern engines, but most of today's engines have clearances on the order of 0.0015 to 0.0025 and require 10W30 or lower viscosies for minimum start-up wear. You eventually reach a point of no additional benefit. You want an oil that provides a certain film thickness at all temps, but not so thick it robs you of Hp. High viscosity oils rob you of Hp by having to churn and push thick oils through feeder passages and bearings. This is called "viscous friction" and any friction robs you of power that would have gone to the wheels. My experience and testing with gas engines, both air-cooled and water-cooled, shows most engines reach a point of no additional benefit at viscosities over 40 Wt. Unless the engine is DESIGNED for racing or hauling, and has large clearances, there is no need for any oil above a 15W40. [ March 11, 2003, 03:16 PM: Message edited by: MolaKule ]
 
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922
Location
Ontario , Canada
I can see both sides of the 5w-30 and 10w-30 argument despite that guy's opinion. A good synthetic 10w-30 will outflow pretty much any 5w-30 conventional oil and is plenty safe in a Honda engine. However, a good 5w-30 synthetic oil can be just as effective as a 10w-30 viscosity at warm temps, and can offer even better flow at colder temps. The differences are probably minimal at either extreme thus not really worth arguing about. I personally would run a good 5w-30 synthetic oil in that engine. With something like Mobil1, you don't have to worry much about viscosity improvers , thus 5w-30 would be as effective as 10w-30 year round in a healthy engine.
 
Messages
1,539
Location
Shippensburg, PA
At what temperature would one prefer a 5W-30 dino over a 10W-30 dino? 0 deg F? 5 deg F? 10 deg F? I understand that 10W-30 is more vis stable, but I am concerned about cold start-up wear.
 

Patman

Staff member
Messages
21,990
Location
Oakville, Ontario
quote:
Originally posted by novadude: At what temperature would one prefer a 5W-30 dino over a 10W-30 dino? 0 deg F? 5 deg F? 10 deg F? I understand that 10W-30 is more vis stable, but I am concerned about cold start-up wear.
Since most 10w30 dinos are not all that great in colder weather, I'd say if you live in an area which regularily gets below 10F in winter, you should definitely be using 5w30. Although my comfort level says that if it's getting that low, it's definitely time for synthetics. Given the choice, I'd rather run a 10w30 synthetic in the cold winter over a 5w30 dino.
 
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