The "bearing skate" issue... was Harley Davidson right?

[LowRider94]

For years, Harley Davidson said that you couldn't run synthetic oil in their bikes because it was too slick and might cause "bearing skate," I think they called it.

I figured that they were just really wanting to dissuade people from using anything other than their own motor oils, and at the time they did not have any synthetic oil to sell you.

When they finally came out with Syn3, they said they had it specially formulated to work with the roller bearings (on the lifters, I assume), so that they would not "skate."

I figured this was all a bunch of crap, too, as HD is prone to feeding folks a steady diet of mis and pseudo information about everything from tires to what kind of wax to use. Sometimes they have a point, often they're just blowing smoke.

But last evening I saw this technical article from a Cummins diesel engine publication, written in cooperation with Valvoline oils:

http://www.valvoline-technology.com/...%20Galling.pdf

If you don't want to wade through the article, suffice it to know that roller lifters can in fact "skate" when the oil "traction" is too low (when the oil is TOO slippery). And this is not a good thing, as it can cause cam lobe galling.

The article is interesting, and Cummins went to a lot of trouble making these tests in 3 different facilities, simultaneously, to ensure their results were valid.

All for what it's worth...

I have been getting great results from 20W50 car oils in my motorcycle, and have about 5 or 6 oil analysis reports to show that Havoline and Valvoline oils will work in the evolution engines. But there is apparently a point, generally (it seems from the article) where the oil is too low in viscosity, and too slippery--where the rollers can stop turning and simply skate along the cam lobe--and create damage.

Dan

[Wild1Poet2]

interesting

I would think if its slippery enough to skate its slippery enough to prevent galling.

[dannytheman]

I have always used Harley oil. Call me dumb, I can handle it. I switched to Synthetic from dino at 15,000 miles. I buy a gallon at a time, beats paying $9.99 per quart.

Thanks for the great info. I'm not as dumb as I thought I was!

[JD]

interesting

I would think if its slippery enough to skate its slippery enough to prevent galling.

I'm thinking the same thing.

Seriously though you have to have some serious lifter problems if the pressure exerted down from the valve spring doesn't generate enough friction to make that sucker turn.

Is this an OIL THREAD?!?!?!

Hey, Oil thread, everybody!

Oil thread! Oil thread! Oil thread!

(This usually brings out the best in us!)

[RacingOrangeRoadster]

interesting

I would think if its slippery enough to skate its slippery enough to prevent galling.

I'm thinking the same thing.

Seriously though you have to have some serious lifter problems if the pressure exerted down from the valve spring doesn't generate enough friction to make that sucker turn.

I think at a low RPM you might be right but at high RPM's it would be a problem because the pressure wouldn't have time to take effect enough to roll the bearing. One of the reasons why you have roller lifters instead of plane push rod lifters is to keep contact with the cam during high RPM's.

[JD]

If your oil film thickness is such that the roller "floats" on the cam lobe, you don't have any metal to metal contact, so therefore you cannot have any wear. I assure you this is not the case. If you have metal to metal contact, which you will I assure you, the lifter roller will roll unless you have some very serious issue with this lifter or the valve spring. Period.

[LowRider94]

The Cummins article shows that galling to cam lobes does occur as a result of the roller skating. Probably what is happening is the roller locks, then begins skating until the oil film is punched through, then you've got metal to metal for a nano-second... then galling occurs.

The solution is of course to use an oil with what they're calling a higher traction number, so that way the rollers continue to roll and not skate. The diesel truck oils (15W40's) are designed for this, and this is probably why HD says they're okay to use in a pinch if you can't get a good 20W50.

Dan

[junior]

i use wesson oil because it is polyunsaturated

j

[Nitram_b4]

i use wesson oil because it is polyunsaturated

j

before or after you cook your fries in it?