In Theory What Weight Oil Provides Better Cooling ?

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Ontario , Canada
Well I get out to one or two road course events each year. There are guys that attend with me who have oil temp sensors with the same vehicle. And they tell me that their oil temps can get pretty high at times during the event. We run a 2 mile closed road course (Gingerman Raceway in South Haven Michigan), we do 15 minute heats running full tilt the whole time. The track has eleven corners, three long straights, high rpms used a lot. I was wondering in theory if a certain weight oil would help better in terms of cooling properties. Would a thinner oil such as 10w-30 provide better cooling than a thicker oil such as 15w-50 because it circulates quicker, or does a thicker oil provide better cooling because it coats the internal parts better. My two choices would be 10w-30 or 15w-50. I have no idea which one would create less friction. My car is a Honda Civic, no oil cooler, stock cooling system, etc..... . Any info would be appreciated. Thanks.
 
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PA
The idea of the oil is not to cool but to simply stay at a useable and stable temperature where it works best. At higher RPMs the thicker 15W-50 is probably adviseable, I know LS6 Z06 vettes show in the owners manual to run a 15W-50 or 20W-50 racing oil and to even run 1qt high when racing (like +1 over normal). The main thing is if your oil is reaching 230 on the track or higher you want that oil to remain thick enough to keep parts from touching under extreme load no matter what. If your engine isn't cool enough you need a larger radiator, or simply more water in the coolant mix. Try water wetter too if you decide to run a 70/30 water/glycol mix. Since you're in canada though I don't know whats adviseable for raceday there - you wouldn't want to show up with a cracked block [Smile] . I think your better bet would be to go with a thicker oil that resists the effects of heat better, under that kind of stress you don't want 10W-30 sheering out.
 

Patman

Staff member
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Oakville, Ontario
I think in that engine you'd have hotter oil temps with the thicker oil, since the oil pump would have a harder time pumping that oil, plus your clearances in that engine are more suited for the thinner 30wt oils. I'd go with no higher than a 40wt for sure.
 

Al

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19,161
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Elizabethtown, Pa
Yea-I don't think cooling is the issue. The thinner oil will take away heat better-But it may get on the far left of the Stribeck-Hersey curve (too little viscosity and too high a load=boundary conditions). You will be generating to much heat and then - [crushedcar] [freaknout]
 
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47,639
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Duvall WA - Pacific NW USA
IMHO - cooling from your oil is important, yet I would still call it a secondary "feature". You should persue improvements to your cooling system (as well as engine/intake) mods before you choose an oil based on it's heat dispersal properties. In fact your "water" cooling system "takes" about 60-70% of the heat from the engine, the remainder goes to the air, the exhaust, and yes the oil. Maybe consider an oil cooler as well (thermostatic of course). THEN you can choose the right oil based on viscosity and friction properties (well ok less friction - less heat - a real good arguement for synthetic oil [Big Grin] )
 

Idrinkmotoroil

Thread starter
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922
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Ontario , Canada
I think the guys were talking about oil temps climbing in the high 200's, so that sounds very high, especially for sump temps as the probes are located in the oil pan. Maybe a 40 weight Mobil1 S.S. would be a good medium weight to run for a track event then. thanks for the replies.
 

Al

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Elizabethtown, Pa
quote:
Originally posted by JSIR: I think the guys were talking about oil temps climbing in the high 200's, so that sounds very high, especially for sump temps as the probes are located in the oil pan. Maybe a 40 weight Mobil1 S.S. would be a good medium weight to run for a track event then. thanks for the replies.
So you're saying that oil temps are measured in the pan?? Is that universally true?? If thats the case then it isn't really that fair (or that meaningfu) to compare the coolant to the oil. Once the block is hot (approx the temp of the coolant), the oil is probably close to that temp as it gets through the oil gallary and reaches the cams and bearings. Although the splash part of it is relavant.
 
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47,639
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Duvall WA - Pacific NW USA
NO doubt, go with an oil cooler and maybe even a remote or dual remote filters - not only is the oil better cooled, you can gain a healthy increase in oil volume - this logic works very well on my Volvo turbo on hot days, with increased boost (VERY hot [Coffee] and hard on the oil)
 
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Oklahoma
Oil is a coolant for certain parts of a motor. Take valve springs for example. If a edge orifice solid flat tappet lifter is used instead of the piddle valve type to reduce the amount of oil going to the top end of a small block Chevy with roller rocker arms the rule of thumb with engine builders is valve spring life is shortened by 40 percent. This is but one way to restrict oil to the top of a pushrod motor. Taking temp readings at the oil pan is a usefull tool in your own engine to see what and how other mods affect oil temp. The Exhaust lobe centerline in relation to the cranshaft in terms of degrees "rotational not temp" would be and adjustment or change that will affect engine oil temp. For those that keep up with Motorcycles you will remember the Suzuki GSXR's and their oil cooled engines 15 minutes is not an Endurance race so a GOOD dino would suffice in some motors but will be hit pretty hard and need changed at some point. The better Syn Lubes available IMO would be better in any type road racing these days depending on engine mods or willing to change often if a dino is used EDIT: When picking a VI of a oil to use in the motor take a look at the HTHS rating as well. If your clearances are more for a 30 wt lets say,you can probably find a 30 wt with the same or better or just plain near enough HTHS as a heavy race oil [ November 02, 2002, 11:03 AM: Message edited by: dragboat ]
 
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JSIR, This issue is a balancing act and must be tested. For endurance road racing like we did with Olds Quad 4's putting out 200 to 300 hp non turbo or supercharged, we ran stock sump capacity but tricked oil systems ( lots of 3 g + lateral) with AC oil filters. Mobil1 15w-50 late 80's early 90's version, Castrol Syntec (PAO) when they sponsored Hemmingson/Olds,Redline various weights, and finally Synergyn 3w-30. I found the thinner weight of the Synergyn to work well and cut appreciable heat while providing super boundary and mixed lube. In a stock Honda for less than 20 minutes of running at a time (with cooling in between) a high quality real synthetic 30 w should give a good balance for you to experiment with. 40% of your cooling is going to be from oil flow so flow rate is critical, a higher vis oil will cause a Honda issues if it can't unload the heat.
 

Jay

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Idaho Falls, ID
I agree with Terry. A thinner oil not only conducts heat better but will heat up less from it's own friction than a thicker oil. The K20A2 and K20A3 engines are water and oil cooled--that is, jets of oil are squirted at the underside of the piston crowns to keep them cool, so the oil is a very important coolant in this engine. Thinner oil will put a little more hp on the ground too. Synergyn sells an oil to Winston Cup racers that's 4 times thinner than water.
 

Idrinkmotoroil

Thread starter
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922
Location
Ontario , Canada
more great info , thanks again guys. Our next event is June 2003, so I have some time to find a suitable oil. Whatever oil I do use, it will just be for the one event, I always swap out the oil after the event - which includes 5 hour drive there and 5 hrs back. Most guys just run a temp sensor lead to the oil pan, it is the easiest place to tap into without causing worries about leakage, dunno if that is the most accurate place to take a reading but it probably suits their needs. Jay I don't know if our cars get all the goodies of the RSX-S k20 engine. I know we don't get their oil to water cooler device that sits under the oil filter. I hope they did give us the oil squirters, but sometimes they don't do that on engines that rev below 7000 rpms, typical Honda cost cutting decision. It would be nice to have those though, I hope to get a shop manual soon and see exactly what they gave us on the lower cost base k20a3 engine.
 
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349
Location
Quebec, Canada
quote:
Originally posted by JSIR: more great info , thanks again guys. Our next event is June 2003, so I have some time to find a suitable oil. Whatever oil I do use, it will just be for the one event, I always swap out the oil after the event - which includes 5 hour drive there and 5 hrs back. Most guys just run a temp sensor lead to the oil pan, it is the easiest place to tap into without causing worries about leakage, dunno if that is the most accurate place to take a reading but it probably suits their needs. Jay I don't know if our cars get all the goodies of the RSX-S k20 engine. I know we don't get their oil to water cooler device that sits under the oil filter. I hope they did give us the oil squirters, but sometimes they don't do that on engines that rev below 7000 rpms, typical Honda cost cutting decision. It would be nice to have those though, I hope to get a shop manual soon and see exactly what they gave us on the lower cost base k20a3 engine.
JSIR, I am assuming - based on your nickname - that your Civic is equipped with the B16A2. To my knowledge, every B-series Honda motor is equipped with an oil cooler. Mind you though, our oil coolers are cooled not by air, but by the coolant using coolant passages. Your oil filter sits literally right on the oil cooler....or at least it should be. And also, after conferring with a VTEC supplement guide for my B16, yours should also have piston squirters as Jay pointed out on for the K20. Mind you though, my B16 is the first generation 88-91, while yours is probably the second or third gen. Either way though, the oil cooler and piston oil squirters should be present in your engine. Heck, you're running higher compression, and wilder cams than mine...so all the more important to have the cooler and squirter, IMHO. Again, I'm assuming you're referring to the Canadian version Honda Civic SiR which is B16A equipped. Regards, Oz
 

Idrinkmotoroil

Thread starter
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922
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Ontario , Canada
quote:
Originally posted by The_Oz: I am assuming - based on your nickname - that your Civic is equipped with the B16A2. To my knowledge, every B-series Honda motor is equipped with an oil cooler. Mind you though, our oil coolers are cooled not by air, but by the coolant using coolant passages. Your oil filter sits literally right on the oil cooler....or at least it should be. And also, after conferring with a VTEC supplement guide for my B16, yours should also have piston squirters as Jay pointed out on for the K20. Mind you though, my B16 is the first generation 88-91, while yours is probably the second or third gen. Either way though, the oil cooler and piston oil squirters should be present in your engine. Heck, you're running higher compression, and wilder cams than mine...so all the more important to have the cooler and squirter, IMHO. Again, I'm assuming you're referring to the Canadian version Honda Civic SiR which is B16A equipped. Regards, Oz[/QB]
Oz, no actually I have the 2002 Civic SiR which is the hatchback with 2.0L k20a3 engine. They definitely do not come with the Honda oil to water cooler. I actually owned a 99 Civic SiR with the b16a engine before this new car, and even it did not come with the Honda oil to water cooler. I did add one to that engine myself however, after tracking down some parts from a Japanese spec b16a , but Honda cheaped out on oil coolers on those cars - even though it was listed in the shop manual as being present! . The first gen. b16a's did have them though. Honda even pulled them off Integra GSR's after 1995 or so, as a cost saving procedure. My 99 b16a did have oil jet squirters, I am just not sure my k20a3 engine has them. I know the Acura RSX-S K20a2 engine has both oil squirters and an oil to water cooler. Knowing Honda they could have cheaped out on my engine like they have on others. [Confused]
 
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349
Location
Quebec, Canada
quote:
Originally posted by MolaKule: Thinner oils go into the turbulent flow mode much quicker than thicker oils, which relate to faster heat removal.
MolaKule, Can you elaborate on what you mean by turbulent flow mode, please? [I dont know] Thanks, Oz
 
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JSIR, I may have a trick oil "brew" that I can't post here that may work wonders for you in both weight and Boundary layer lube at low cost. Email me. TD
 
Messages
349
Location
Quebec, Canada
quote:
Originally posted by JSIR: Oz, no actually I have the 2002 Civic SiR which is the hatchback with 2.0L k20a3 engine. They definitely do not come with the Honda oil to water cooler. I actually owned a 99 Civic SiR with the b16a engine before this new car, and even it did not come with the Honda oil to water cooler. I did add one to that engine myself however, after tracking down some parts from a Japanese spec b16a , but Honda cheaped out on oil coolers on those cars - even though it was listed in the shop manual as being present! . The first gen. b16a's did have them though. Honda even pulled them off Integra GSR's after 1995 or so, as a cost saving procedure. My 99 b16a did have oil jet squirters, I am just not sure my k20a3 engine has them. I know the Acura RSX-S K20a2 engine has both oil squirters and an oil to water cooler. Knowing Honda they could have cheaped out on my engine like they have on others. [Confused]
Wow! Thanks for the clarification there. Who would have thought that Honda would do such a thing, considering their reputation and all. Thanks, Oz
 

Idrinkmotoroil

Thread starter
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922
Location
Ontario , Canada
quote:
Originally posted by Terry: JSIR, I may have a trick oil "brew" that I can't post here that may work wonders for you in both weight and Boundary layer lube at low cost. Email me. TD
that sounds interesting Terry, I will hit you up shortly. thanks.
 

MolaKule

Staff member
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OZ, Laminar flow is when all the fluid layers flow in the same direction and at approx. the same speed. Visualize laminar fluid flow as arrows of streamlines all pointing in the same direction; some of the streamlines (fluid layers) will be moving slower near the walls than at the center, due to resistance of the walls. In turbulent flow, you have curls, eddies, etc of the fluid layers (similar to the water at a dam spillway, the water churns at the bottom). Turbulent flow means the curls and eddies change direction of flow at times (doubling back in some cases over a short distance) so the fluid represents an actual increase in surface area, carrying off more heat. In an engine, most of the flow is turbulent, with the only laminar flow being seen in pipes or oil channels, such as the oil channel in a crankshaft.
 
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