E: Engine Oil Viscosity

[greg brillus]

Like tire technology, oil and other lubricants are light years ahead of those from the old days. On engines like the Vincent that have tiny oil ways and passages, a thinner oil has a far better chance of lubricating all the important parts than thick oil. I used MLR 40 castor in the race bike and even though the rear cam snapped into pieces from valve spring failure, the cams and followers were buggered anyway. I felt the oil was too thick........It is immediately after start up of any engine that damage happens, so the ability of the oil to move quickly and get to vital parts is far more important in an engine than if it looses too much viscosity due to running hot. We all know (or need reminding) that the Vincent engine is not a hot running engine with regards to its oil temperature. Unless you are running sewing machine oils.......Pretty much any modern oil will do. My trial just proved to me that using a thinner weight of oil is better in these engines than a heavy oil for more reasons than that which might not seem obvious. Cheers...............Greg.

 

[Robert Watson]

The oil debate will rage for ever.

I run Valvoline VR1 in all my Vins, and her Mini. It has the cat converter killer ZDDP which is what we need for flat tappet engines, ie sliding friction versus rolling friction. Never give it a second thought.

 

[Michael Vane-Hunt]

This stuff.

 

[Martyn Goodwin]

I have hesitated to chime in here as I was not sure that my memory was clear. I have now checked my archives and dug out the following.

MPH #182 - In it a letter Phil Irving wrote to Harpers is quoted as follows: "cam wear is traceable in very many cases to people using too heavy a grade of oil. SAE 30 is too heavy where the engine is used for short runs and is not warmed up before working hard".

In MPH 233 Phil states " If you only do short runs you only need a couple of pints in the (oil) tank and thin oil at that!" He also tells that over-revving when cold with thick oil will quickly destroy a engine.

Then in MPH #392 Phil offered the following advise "Do NOT use multigrade oil in your Vincent if you would like the cams to last a reasonable mileage

So Greg it seems you are on the right track. Looks like a mono grade SAE 30 may be a good starting point; or a multi grade with 30 or 40 being the upper (thicker) end of its range. Penrite, Shell, BP, Valvoline and I am sure many others offer such oils. I reckon no matter what you choose, as long as its not too thick, it has to be better than what was available 70 years ago!

 

[Bill Thomas]

I have hesitated to chime in here as I was not sure that my memory was clear. I have now checked my archives and dug out the following.

MPH #182 - In it a letter Phil Irving wrote to Harpers is quoted as follows: "cam wear is traceable in very many cases to people using too heavy a grade of oil. SAE 30 is too heavy where the engine is used for short runs and is not warmed up before working hard".

In MPH 233 Phil states " If you only do short runs you only need a couple of pints in the (oil) tank and thin oil at that!" He also tells that over-revving when cold with thick oil will quickly destroy a engine.

Then in MPH #392 Phil offered the following advise "Do NOT use multigrade oil in your Vincent if you would like the cams to last a reasonable mileage

So Greg it seems you are on the right track. Looks like a mono grade SAE 30 may be a good starting point; or a multi grade with 30 or 40 being the upper (thicker) end of its range. Penrite, Shell, BP, Valvoline and I am sure many others offer such oils. I reckon no matter what you choose, as long as its not too thick, it has to be better than what was available 70 years ago!

It also helps if the Cams are made of the right stuff !, Which a lot of old Vincent ones were not.
We had the same in the motor trade , With Ford and Vauxhall, No amount of oil will Make up for badly made parts. Cheers Bill.

 

[greg brillus]

I agree on all so far remember this is a topic on how viscosity affects the ability of the engine to turn over for easier starting. I had a feeling that the castor oil i was running in the racer was too thick, and I use to pre oil the engine before each event squirting several shots of fresh oil down each pushrod tube before the first start of the day. Perhaps the valve springs were set up too stiff, but the cams/followers only lasted two years, and you don't get much of a chance to warm up a Vincent on the race track before the actual race starts. If I were to build another Vincent race engine I would completely revise the oiling system similar to what the Horner's did when they built the Goodwood bike. Roller bearing cranks definitely do not need heavy oil. Just try squirting oil through some of the small engine fittings with an oil can and you will see how restrictive the system is .......With the feedpipe banjo undone from the engine see how slowly a thicker oil takes to empty the oil tank................

 

[Bazlerker]

I have hesitated to chime in here as I was not sure that my memory was clear. I have now checked my archives and dug out the following.

MPH #182 - In it a letter Phil Irving wrote to Harpers is quoted as follows: "cam wear is traceable in very many cases to people using too heavy a grade of oil. SAE 30 is too heavy where the engine is used for short runs and is not warmed up before working hard".

In MPH 233 Phil states " If you only do short runs you only need a couple of pints in the (oil) tank and thin oil at that!" He also tells that over-revving when cold with thick oil will quickly destroy a engine.

Then in MPH #392 Phil offered the following advise "Do NOT use multigrade oil in your Vincent if you would like the cams to last a reasonable mileage

So Greg it seems you are on the right track. Looks like a mono grade SAE 30 may be a good starting point; or a multi grade with 30 or 40 being the upper (thicker) end of its range. Penrite, Shell, BP, Valvoline and I am sure many others offer such oils. I reckon no matter what you choose, as long as its not too thick, it has to be better than what was available 70 years ago!

Hmmm, time to re-evaluate my oil of choice..Thank Heavens I have a few cases of Brad Penn 30wt..

 

[greg brillus]

Yes the engine definitely spins over much "Free'er" with a lesser weight oil. I don't think it seems obvious until you try it and see (feel) the change. A heavy weight oil in a cold climate would make starting a challenge I would have thought.

 

[Bazlerker]

I have never tried to start my Vincent in the dead of winter even with the 30wt oil it gets in the fall..but our Honda uses 0w-30, which I am sure helps it turn over, and get oil to the top end quickly during the -40 ( or colder) winters that we have here..

 

[Mikethebike]

View attachment 17082 This stuff.

Hi all. I think you've hit the follower on the cam with your mention of zinc, Greg. I've just been alerted to the dangers of modern oils, with little or no ZDDP content, and have switched to the Valvoline VR1 shown above - the thing about using diesel oils appears to be that they contain this stuff anyway, as they're more highly stressed. https://www.thoughtco.com/debunking-the-motor-oil-additive-urban-legend-726162