OHC Engines and Viscosity

[msparks]

I think how your going to use the vehicle should also be considered. Overall, if you are getting the oil to full operating temp for a good while then 0w40 would be a good choice. If you are not, then the Xw30 would be better because it is designed to flow better at a cooler temp-relatively. Ie, Xw30 will flow better at 160-180 degrees than a Xw40, but when you get up over 200, I say the difference would be splitting hairs.

 

[TooSlick]

Forget about the comparison of cold pumping properties ...the point I was trying to make is that the 0w-40 or 15w-50 is too thick once the engine has fully warmed up. This is especially true in cold weather .... Oil does more that just lubricate, it also cools the engine and removes particles that are generated as part of normal wear. All things being equal, a xw-30 oil will circulate more rapidly and do a better job of cooling the engine. I go back to Bobs analogy about the candy bar ...if one is good are ten necessarily better? There is NO benefit to using an oil that is thicker than necessary to do the job and there are several drawbacks to doing so: 1) You lose fuel efficiency 2) The engine and seals run hotter 3) You lose power at the top end due to increased friction. 4) Running very high oil pressure all the time isn't good for pressurized engine seals 5) If you run a thick oil in an OHC engine in very cold weather, you can get increased valvetrain wear. If you have any doubts about the grade of the oil you are using, install an accurate oil pressure gauge - at long as you are getting adequate oil pressure under all conditions there is little if any benefit to be gained from using a thicker oil. TooSlick

 

[Dr. T]

Some good points being made here, but the only thing I'm disturbed by is: "the O doesn't mean anything to me". Huh? This is the only true indicator of cold pumpability. It is more important than the viscosity at 40 C. Remember, this is 104F! Do you not think any and all oils flow at this temp? What about the VI at 100C...this is 212F (ouch). Remember, oils don't get thicker at temp. Why do they have the 2 numbers...I'm not an engineer, but it always helps to compare numbers along the scale...we have 2 numbers for cranking ability...and here we have 2 numbers to compare for warm/hot temp. viscosity/flow. The 0-40 has a cold cranking numer of 4,301 @ -35°C (-31F) contrasted to the 5-30 which is 10,250 @ -30°C (-22F)...more than twice as thick! So, does the 0-40 flow better than the 5-30 at super cold temps? Absolutely. Is it thicker at hot temps, thereby providing utmost in film thickness and protection from wear? Absolutely. Can you use it all year in even the most extremes of temperature differences? Absolutely.

 

[Giles]

quote:

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Originally posted by Dr. T: So, does the 0-40 flow better than the 5-30 at super cold temps? Absolutely. Is it thicker at hot temps, thereby providing utmost in film thickness and protection from wear? Absolutely. Can you use it all year in even the most extremes of temperature differences? Absolutely.

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If I'm concerned about cold starts being where most of the engine wear occurs, the super cold temps don't matter for me in my case. How quickly does the engine get lubrication at 0-20 degreec C is more important (California weather). Maybe there isn't enough of a difference to care I don't know but the specs don't give us a number in that range. I would be tempted to try the 0w40 myself but would like to see more wear numbers to back it up. The argument to use 0w30 instead of 5w30 is more obvious I think than comparing the 30 and 40 weights because the 0w30 will always be a bit thinner upon a cold start than the 5w30.

 

[Dr. T]

Giles, first off, these oils are more appropriately designated for temps. at or around the -35 C (-31F) range. (ie. 0C is a joke) by the SAE. So, a 0-20, 0-30 and a 0-40 will all be the same when it comes to "how fast will the engine be lubricated at -35 C" because at this temperature, they will roughly be at the SAME thickness. Since O C is a joke, all these oils will flow adequately to lubricate one's engine. Don't know what you guys want re: flow. Do you guys think of "flow" as in a "shower" or "waterfall" in the engine? As long as there's a "coating" of oil on all the parts, they will be readily lubricated up until the point where the oil begins to flow and pressure is reached ie. 1-2 seconds...or we'd all be in trouble.

 

[dragboat]

Quote By DR T: (The 0-40 has a cold cranking numer of 4,301 @ -35°C (-31F) contrasted to the 5-30 which is 10,250 @ -30°C (-22F)...more than twice as thick!) Now ya gotta get your numbers straight when trying to prove a point,this one is getting you no where The cP of the 0/40 is 4301 @ -35C the cP of the 5/30 is 3600 @ -30C You had one Mini-Rotary Viscometer ( MRV TP-1 " method and another ASTM Method used in that quote,nice try though BTW,that 10,250 you posted is the 10/30 oil not the 5/30. Now instead of using these data sheets I propose a guy goes to an Autozone right when they open and before the heater is turned on,pick up a bottle of each oil and shake them. Undeniable evidence the 0/40 is thicker than the 5/30 Better yet,let the fellow who created this topic call Mobil and ask which oil is the better winter oil and post their reply,,DR T,no offense but I beleive you are a thicker is better type pushing your opinions on another guy asking questions,,go ahead and run your thicker oil all year,your opinion have been posted in duplicate .Matters not to me but for the last time,it is only common sense that says in the same line of oils to use a lower vi oil during winter months,,sure he might could use 0/40 and he also might be using it for very short trips of a mile or so,the 0/40 will NOT warm up as fast as the 5/30 will period during the winter. Some think these new oils will do it all,they come close but there still are 4 seasons on this Earth,winter is one and usually a thinner VI oil is used when available,in this case it certainly is available, Now I am outa this thread for good, Fred,once again please call Mobil and ask them which oil during winter for your car,your driving and your coldest cold starts,,,the deal about changing oils for a 1 hour trip or whatever was out of context deluxe BTW And about the 0 meaning nothing to me? Ask anyone who knows anything about Redlines 10/40 if the 10 means anything to them [ January 06, 2003, 06:51 PM: Message edited by: dragboat ]

 

[G-MAN]

quote:

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Originally posted by dragboat: Now ya gotta get your numbers straight when trying to prove a point,this one is getting you no where The cP of the 0/40 is 4301 @ -35C the cP of the 5/30 is 3600 @ -30C

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Dragboat, I agree 100%, which is why you can't compare the cP of these two oils and say that the 0w40 is thicker than the 5w30. They aren't measured at the same temp, so it's apples and oranges. Drop that 5w30 down to -35*C and I guarantee you it will have a higher cP than the 0w40.

 

[Dr. T]

Ooops, sorry...you're correct. That number is for the 10-30 (I copied and pasted the wrong column from M-1 website) but not the wrong temperature for comparison. That is, the 5-30 ACTUALLY shows 12,700 @ -35° C whereas the 0-40 is 4,301 @ -35° C. ie. this shows that at that temperature (-35 C), the 5-30 is 3 times thicker than the 0-40, hence the 0-40 will pump better at that temperature even though both oils show pour points below -48 C and pumpability limits of greater than -46 C (the purpose of this thread and initial posted question). I agree we all have different opinions and should try to be objective when posting. Discussions are good..all opinions welcome. I don't agree that a 0-40 will not warm up as quick. All oils should warm equally when an equal amount of heat energy is applied to them. How they dissapate it is a different story. Isn't the general consensus here that thicker oils don't dissapate heat as well? So, do they take longer to warm up? I don't know... But, we're not saying the 0-40 is thicker, so it should actually warm up easier. But, again I'm not sure I believe this. In the store...is the 0-40 thicker? It may be...remember, we're out of the freezing range and somewhere under 40C but over -35C, the 2 oil's viscosities cross...I don't know where that is....but, I can't tell the difference in thicknesses from a closed bottle?

 

[smeltjr]

Now I am completely confused and this is starting to sound like a shell game, buying a bed mattress, or figuring out the flex in a golf shaft. My sled (beater?) (car to get 45 miles each way to work economically?) (whatever other euphemisim i can come up with-it does purr)is a 90 acura integra with 122k. Manual calls for 5w30. I live in metro Chicago, it can get quite cold (0F or below)though we are having a mild winter. I got some Schaeffers Supreme 10w30 (older engine, higher miles, syns and syn blends are supposed to pump better cold, etc) which I was gonna use year round. Now I'm not so sure. Below is what i came up with from the Mobil data above, the Schaeffer data on this site, and Pennzoil's site (i am running the Pennzoil in 5w30 for its 2nd auto rx treatment was then going to use the Schaeffers) Schaeffers 7000 5w30 5073 @ -20C Schaeffers 7000 10w30 4500 @ -30C Schaeffers Micron Moly (dino) 5w30 6000 @ -30C Schaeffers Moly Pure Syn 5w30 2100 @ -25C Pennzoil SL 5w30 3300 @ -25C M1 5w30 12,700 @-35C M1 0w40 4301 @-35C Now, the Schaeffers #s contradict just about everything i've read on here about syn vs dino. The pure syn appears that it MIGHT JUST be the thickest but can't tell as all done at 3 diff temps. Why? But it is certain that Pennzoil dino 5w30 pumps that much thinner than the Schaeffers PURE SYN????? I just don't know whet the h*** to put in the car when the auto-rx is done (fortunately if mine dies, I ain't out as much as some of you-but that begs the question of what to put in my wife's 2000 minivan). Maybe I'll just use supersyn 5w30 the rest of the winter and drain it out in summer and use the Schaeffers 10w30 then. These guys should all have a comparison of consistency. This makes no sense.

 

[Pops]

smeltjr wrote M1 5w30 12,700 @-35C M1 0w40 4301 @-35C haha,reread dragboats numbers. those two you and DR T posted are two different methods of testing VI,,that is why DR T thinks the 5/30 is 3 times thicker how he arrives at that I don't know but for sure those are two different vi tests,mobil has them rated in both tests and dragboat posted clearly the differences. please see the humour in this difference in the vi numbers and how they are come by yet unknowingly posted wrong by DR T. Go to the mobil site and you will see for yourself

 

[smeltjr]

I see. M1 data is as follows. 5w30 [email protected] -30C 0w40 [email protected] -35C Now any input on the Schaeffers anomaly. It now seems that the Schaeffers 7000 has as good a cold crank in 10w 30 as M1, but the dino micron moly 5w30 beats em both at 6000 at -30C? WAIT! Does any of this really matter and will I be hurting my engine with Schaeffers 10w30 in Chicago winter? I guess that is the only answer I was looking for.

 

[Dr. T]

Once an oil has warmed up, what difference is the rate of flow? The candy bar analogy is true, but so is a thinner oil at temperature...it runs too much...flowing out of high pressure areas leading to wear. Not to mention increased oil burn off, settling out of oil contaminants on engine parts, sludge formation, varnish...all detriments to an engine which happen at operating temperature...not when you first start the car! If a 5-30 were adequate, then we'd all be using this and nobody would be showing Toyota engines sludged up from "proper" regularily scheduled maintenance at the Toyota dealership...and Toyota wouldn't be doing a recall. Nor would we be arguing about going beyond 3k mi./oil change intervals.

 

[Ken2]

T SAE J300 specifies the test temperature and needed viscosity to meet the spec for a certain "weight." 0W must be no higher than 6200 cP and tested at -35°C 5W <6600 cP @ -30°C 10W <7000 cP @ -25°C 15W <7000 cP @ -20°C 20W <9500 cP @ -15°C 25W <13000 cP @ -10°C So, it can be hard to find the info to compare oils of different viscosities at the same cold temperature. All oils are tested hot @ 100°C Ken

 

[Dr. T]

Can someone clarify the statement re: the 2 methods of VI testing??? If one goes to Mobil's website, they can see the "Cold Cranking #'s (cP @ C)" for all their oils. The number are posted in with respect to 2 different temperatures for comparison. eg. -25C and -30C. So to properly compare one grade to the next with respect to viscosity, one needs to look at the same temperature. So, to compare (from the above posted #'s): M-1 5-30 is 3,[email protected]° Schaeffers Micron Moly (dino) 5w30 is 6000 @ -30C (Schaeffers 7000 5w30 5073 @ -20C) (Schaeffers Moly Pure Syn 5w30 2100 @ -25C) (Pennzoil SL 5w30 3300 @ -25C) M-1 10-30 is 3,848 @ -25°C Schaeffers 7000 10w30 is 4500 @ -25C (NOT -30C!!) The 5-30 comparison shows that the Schaeffers is 1.67 times (or 67%) thicker than M-1 at -30C. The 10-30 comparison shows that Schaeffers 7000 is 1.17 times (or 17%) thicker than M-1. The numbers are so close that you can go with either. The other 2 Schaeffers numbers cannot readily be compared (without extrapolation) as M-1 doesn't post #'s on the current PDS (that I'm aware of) for the 5-30 at -20C nor at -25C. From what I can see, extrapolation becomes difficult because an oil can drastically change (eg. thicken) at a certain point in time per degree C. Other than to say that the Schaeffers Moly PureSyn 5-30 is about 1.57 (57%) times thinner than the Penzoil SL 5-30 at -25C. As far as safety of an oil in the winter...first stick with manufacturer's recommendation for oil grade. Otherwise, if you want to play engineer, look at the "pumpability limit" or "borderline Pumping temperature" #'s...which should be about 10-15F above the Pour point to determine the maximum safe limit of an oil. Don't know where you guys see the humor though...we're all just trying to sort out the specs...which not only don't paint the whole picture, but are incorrect at times!