| Author | Message | ||
     Rick |
I was watching a program on Nascar engines and the oil they are running and it started me wondering: They are running Nascar engines at 10,000 rpms for 500 miles on zero weight oil with no failures. The commentator said they are finding that the engines run cooler, with less friction and more power and they are not experiencing any engine failures associated with oil. In fact, they are tearing the engine down after 500 miles on the dyno at 10,000 rpms and finding no wear at all. So, why are we running 20-50 weight oil in an engine that runs at much slower revs. I'm just wondering and I will be the first to admit, I don't know much about the subject...anyone have any idea's on this? Rick, 97 S1 | ||
| Bigj |
Because they tear it down every 500 miles. They are also liquid cooled engines. | ||
| Ftd |
Rick The number refers to viscosity. In general, you want a high number (viscosity) in high temp. situations and the opposite in low temp. situations. Mobil makes a 0W-30 synthetic oil which is for use up north in the winter time. Helps with cold starts. As I understand it NASCAR teams use 0W oils for qualifying only (less HP loss from oil viscosity) but use 20W-50 for the races. Frank | ||
| 1320 |
Don't know about street use..but at the dragstrip a whole slew of v-twins are using 0-5 weight oils with great success. | ||
| Fullpower |
i run 0W-30 synthetic in my race car. sportsters get 15W-50 synthetic. wifes jeep cherokee gets 10W-30 synthetic. not real anal about brand names. have used mibil one, amsoil, valvoline, chevron. whatever is available at oil change time......clean oil is good. dean | ||
| Ftd |
Liquids' viscosities decrease with an increase in temperature. Ever wonder how multi-weight motor oils do the opposite? Frank | ||
| Rokoneer |
Just because: The Honda Element pseudo SUV come stock from the factory with 5w-20 wt oil in it and factory recommended 5,000 mile oil change intervals. | ||
| Fullpower |
first oil change on xb12: mobil one 15W-50. put amsoil 75W90 in trans. seems to like it just fine. | ||
| Fullpower |
rick, i would not advise using any real low viscosity oils in an air cooled engine. the bikes see higher oil temps then my water cooled race car. 0W-30 is fine for 15 lap heats on the 3/8 ths mile ice oval. oil is just getting warmed up, dont have gauge, but wild-ass guess says oil temp probably max at around 270 degrees F in the race car. and that peak temp only lasts 3 or 4 minutes at end of a heat, then cools down fast at idle. stuck in slow traffic, the cylinder head temp of a buell is just scary to think about. stick with the 50 weight in the bike. unless you are having starting prtoblems in the winter...........................dean | ||
| Ray_maines |
Dean says: "...whatever is available at oil change time......clean oil is good." (Doing my best Elvis impersonation here) "Thank you. Thank you very much!" I like to use the same brand of oil all the time but I don't really know why. I swear to God, you could run peanut butter in your bike if you changed it often enough. Frank: Multi weight oils DON'T change viscosities. That's the whole trip. When it gets hot out they stay the same, when it gets cold out they stay the same. Obviously, 0w-5 is thinner to start with than, say, 10w-40 but no matter how cold it gets the oil wont get any thicker than a "normal" 5w oil would get. The 10w-40 will only get as thick as a single weight 40w oil would get. Same in the summer except now we talk about being thin and use the lower number. | ||
| Blake |
Zero weight at room temp has about the same viscosity as 50 weight at 200F. So a 0W50 will not change viscosity over temperature. A 20W50 will suffer a loss of viscosity over temperature. There is a chart in the knowledge vault that portrays the relationship between viscosity grade temperature and actual viscosity. Do not confuse "viscosity grade" (20W50) with acutual viscosity (goofy sounding units like centistokes), they are two different things. Rick, The nascar engines also use a massive oil reservoir and lots of oil and a massive oil cooler. The higher the relative velocity between lubricated surfaces, the lower the viscosity needed to maintain hydrodynamic lubrication (keeping the surfaces from touching). Consider going 70 mph in a car and having it hydroplane over a section of road covered in water (very low viscosity fluid). The viscosity is very low, but the speed is high and the hydrodynamic layer of water is able to separate tire from road. That there be lubrication that you don't want. Same occurs in engine journal bearings. They save a ton of power using the lowest possible viscosity. Good for HP in an engine running under load at consistently high speeds, not good for the extreme varied conditions imposed on a street bike, and probably not good for roller bearings. Interesting observation though. Where did you read about it? I have been looking for info on piston speeds of the Winston Cup cars with no luck. I know the 10K rpm and the displacement, but cannot find any info on bore or stroke. Any idea? | ||
| Ftd |
Ray, So the question should be why do the viscosities of multiweight oils stay the same as temps increase vs single weight oils that have decreasing viscosities with increasing temps.? edited by ftd on December 02, 2003 | ||
| Crusty |
The viscosities of multi weight oils do not stay the same as temps rise. They just thin at a slower rate. E.G. a 10w-40 oil flows like 10 weight oil at room temperature, and like 40 weight oil at 220 degrees F. It's a lot thinner, and flows faster at 220 than at room temp. That's why hot Mobil 1 flows faster than Mobil 1 at freezing temps. edited by crusty on December 02, 2003 | ||
| Fullpower |
additives called Viscosity Index Improvers. VI improvers are coiled polymers that " unwind" at a particular rate with temperature change, thus counteracting the natural inclination of the fluid oil to "thicken " as it cools. conversely these polymers wind up with warming temperature to thicken the oil when hot. so in effect these additives stabilize the absolute viscosity over temperature. synthetic oils are inherently more stable with temperature changes, and need less VI improver additives..............dean | ||
| Ray_maines |
right on, ya'll! | ||
| Ftd |
Dean, Is it possible that you are on the right track but have it backwards? Polymers are coiled at lower temps (acting like ball bearings thus less viscous oil) and then straightening out into rodlike structures at higher temps. (thus taking up more area and the shape being less conducive to flow causing close to the same viscosity as the oil had at lower temps)? Frank edited by ftd on December 02, 2003 | ||
| Ftd |
Found this on an oil company site: "Multi viscosity oils work like this: Polymers are added to a light base (5W, 10W, 20W), which prevent the oil from thinning as much as it warms up. At cold temperatures the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. The result is that at 100 degrees C the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot." Frank | ||
| Ray_maines |
I'm not sure, but I think that's what I just said. | ||
| Fullpower |
ftd yeah you got it right. now how do i reset my tps zero?.......................dean | ||
| Ftd |
Dean, Go to a HD shop and pay for 1/2 hour labor and pray they do it correctly (unfortunately). FTD | ||
| Firemanjim |
Alot of race bikes use these 0 weight oils also.There was an article in one of the bike mags in about august of this year talking about HP picked up on dyno with just a change to one of these oils. |
