Question for engine builders. 60 weight oil

[Nosmo King]

Last night I watched the 'Tuttles' motorbike show on Discovery channel. They were building a chopper for Shelby and the motor was put on the dyno to break in. Well they sized it up and did considerable damage that they came to the conclusion was because they used 60 weight oil and this oil was very cold when they poured it into the oil sump.
What is the possible reason an engine builder would specify a 60 weight oil?

 

[55Test]

I believe cycle manufacturers recommend a 60 weight oil because the bikes use a common sump for the engine and gearbox. A gearbox can really shear the life out of an oil so they need an extra thick oil to help combat viscosity loss.

 

[nickmckinney]

That is the common weight for Harley engines. I think that show proved that its not always the correct weight.........

 

[Pablo]

quote:

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What is the possible reason an engine builder would specify a 60 weight oil?

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the paranormal

Seriously - there are reasons like extreme fuel dilutions with rich running conditions and loose bore fits....not sure if these guys just went by old mythology, though.

 

[JohnBrowning]

I think 20W50 is probably the most popular weight with Harley owners from my limited experince! Once you leave the Harley crowd 5W40,10W40,10W60,15W40,15W50 are all popular with import bike owners!

A traditional air cooled Harley V-Twin does not share it's motor oil with the gear case they are seperate. Import bikes on the other hand usualy do share a common sump! Harleys used to run very hot and needed a thicker oil to make up for their lose tolerances. While they are no longer any where near as lose as they used to be old habits die hard! An SAE 60Wt. is insane and has no purpose in amodern motorcycle being built in N.Y. it is gets too cold to not use a multiviscosity. If he wants to use a 60Wt. make it a multiviscosity like Castrol 10W60. In the engines you see in OCC's bikes he would be far better served by a 15W40!

 

[Rob Taggs]

I saw the same show too. These guys need to take a course in engine building and lubricants. I have a friend who owns several Harley Davidsons and only uses 60 and 70 weight Kendall motor oil. He did nearly the same thing on a Sportster. He had the motor rebuilt just dumped in 60 weight Kendall and took off like a bat out of **** on it down the street. About an hour later he had a totally useless motorcycle. He tore the motor up. I preached to him not to put what is Nitro Methane Racing oil in a new motor. I told him to put in a good 20w-50 oil to break it in and stay with that weight afterwards. Don't know if he took the advice.

 

[Propflux01]

If memory serves me correctly, 60w was used on the iron-headed Harleys only.

 

[427Z06]

blupupher, I like your theory best. Also, I would think assembly lube would be a critical factor when a new/rebuilt engine is fired up for the first time.

 

[blupupher]

Their reason for using a 60 weight was probably because the motor was supercharged.
The problem was 2 fold, the oil they put into the engine/oil tank had been stored in drums next to an open door, temps were in the 30's. Second, the oiling system they were using was not working as they had designed. They had to move the oil holes from the uper middle to the bottom of the oil tank. The second engine seemed to work fine once they got a properly working oil presure gauge on it, with 60 weight oil.