RPM limit for oil

[HRD]

While I was looking around the net for different oils, I came across http://www.klotzlube.com/. I looked at the tech sheet for their 10w30 oil and noticed that it had a RPM limit rating of 10,000RPMs.

Two of our cars rev to 9,000rpms.

I had never thought or heard about oil having a rpm limit before and got me thinking what rpm limits other oil may have?

Any thoughts or knowledge on this subject as I am ignorant about it?

 

[AndyH]

Sorry to take this thread O.T., but with a name like "Klotz" I'd be afraid that running this oil would cause "clots" (think "blood clots") in the passageways of my engine.

 

[ToyotaNSaturn]

From the untrained eye, lubricants will get hotter as they see sustained RPM increases, so that means they'll thin-back. Even a 50wt oil would be fine far above 10K I would think....

Klot'z logic does seem odd, though. Isn't akin to Shell or Amoco telling the customer: "don't use the gasoline in your tank beyond 400 miles" ??

 

[radiometer]

I wonder whether such high RPMs might introduce air bubbles into the oil by the high speed movements of the engine parts. I can well understand why that would be a problem.

 

[Jimbo]

It has to do with the fact that the load on a connecting rod journal bearing goes up with rpm. A hydrodynamic "wedge" of oil is necessary to prevent metal to metal contact.

Japanese road motorcyles are an example of 10,000+ rpm applications, and 10W-40 is an almost universal recommendation.

 

[Ken2]

The real concern is the peripheral speed in the bearings, not the rpms. Of course, peripheral speed depends on the bearing diameter and the rpm.

A speed limit for oils is not something I've seen discussed.


Ken

 

[Blue99]

Note that the Klotz Racing 10W-40 has an RPM limit of 12,000 and that the 20W-50 product is listed as unlimited.

Makes me think it is a usage guideline relating to viscosity thinning.

10K rpm and above has got to generate alot of heat transfer from the piston bottoms. Fuel thinning is another issue with racing oils.

 

[Curious Kid]

That's interesting Blue99 - the viscosity notation, for I thought thicker oils would have had some lower rpm use suggestion...but I guess it makes sense as the oil would simply run hotter and thus thinner. A thicker oil I thought would result in whipping of the oil film leading to increased tunning in boundry lube phase, aside from added pumping strain. Warm-up would be of great benefit here.

Mind you, I'm no engineer.

 

[LarryL]

The rpm limit is not the oil, it's the engine. If the engine is not designed to turn high rpm it does not matter what oil you use. I think you have to look at the Klotz claims as advertising. It does not mean that other oils are not capable of such engine speeds, too.

 

[HRD]

LarryL - I guess I am reading it more like ToyotaNSaturn is, that it is saying don't use this oil if the engine revs higher than 10,000rpms, and not that other oils are or aren't capable of such high revs. The 'claim' is in their tech info and not in the generic adverstising blurb.

 

[LarryL]

NASCAR guys mess with main bearing diameters because of surface speeds. They will actually accept a potentially weaker crankshaft to get the bearing speed right where they want it to reduce stress. The same is true in engines designed just for racing.

 

[Big Jim]

One of the complaints about Pontiac engines back in their heyday was that the crank journals were TOO BIG.

 

[daemonite]

motorcycles use 10w40's for redlines upto about 14,000+

i dont see an issue with RPM's, just heat...

V-twins produce much more heat since they are air cooled so they go with a 20w50, high revving car engines and motorcycles do fine with a 30 or 40 weight regardless of RPM (although high revving engines tend to shear oils)

My friend'scelica redlines at 8600rpm, and my other friends builtup 4AGE AE-86 Corolla Trueno redlines at 9000rpm...both of them use 5w30...no issues. Same with my friend's high redlining S2000...5w30 no issues...

Just stick with a shear resistant oil and make sure that you don't overheat.

 

[Shannow]

Unless the manufacturer knows the engine in question, such a recommendation is meaningless.

 

[LarryL]

My V-twin is water cooled and has to be pushed quite a bit to heat up. I use 10w-40 but this engine won't ever see 10 grand. Can you say 'go to jail'.