Author Topic: Oil Question... no, not that kind of question. ;o)  (Read 1831 times)

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Offline Bob Wessner

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Oil Question... no, not that kind of question. ;o)
« on: May 14, 2012, 09:02:38 am »
I've seen several references to folks changing the weight of the oil they use from 10w40 to 20w50. This would seem a decent idea for folks living in hot climates. Here in Michigan, we only average 10-12 days per year with a temp equal to, or greater than, 90F. Even those extremes can be avoided by riding early, etc. so I still run 10w40.

I wonder, why not use 10w50 rather than 20w50 if one is concerned about higher temps. The 10w is still there for faster circulation on cold start and cooler weather, but you have the protection of the 50 under heat and load.

Just a curious question.
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Offline Dimitri13

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Re: Oil Question... no, not that kind of question. ;o)
« Reply #1 on: May 14, 2012, 09:15:54 am »
Because I can't find 10w50 moto oil.

Offline Duke McDukiedook

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Re: Oil Question... no, not that kind of question. ;o)
« Reply #2 on: May 14, 2012, 09:19:16 am »
I think if your were really concerened about heat breakdown you could run a full synthetic 10W40.
I think the availability factor would definitely be big, do they make moto 10W50?
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Offline Bob Wessner

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Re: Oil Question... no, not that kind of question. ;o)
« Reply #3 on: May 14, 2012, 09:29:47 am »
do they make moto 10W50?

Sure. Just do a Google search. Whether they are suitable for our clutches, not sure, was never interested enough to pursue it.
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bollingball

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Re: Oil Question... no, not that kind of question. ;o)
« Reply #4 on: May 14, 2012, 09:41:45 am »
Just about all the big oil companies make 10w50. Just google it. In his book HondaMan recommends 20w50 syn.

Ken

Offline Bob Wessner

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Re: Oil Question... no, not that kind of question. ;o)
« Reply #5 on: May 14, 2012, 09:43:40 am »
I guess, that's my question, why recommend 20w50 rather than 10w50 giving up the lower viscosity on cold starts?
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Offline dave500

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Re: Oil Question... no, not that kind of question. ;o)
« Reply #6 on: May 14, 2012, 01:05:09 pm »
10/50 will have additives to make it such a wide multigrade and will contain those slippery molecules we dont like for wet clutches.

Offline Duke McDukiedook

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Re: Oil Question... no, not that kind of question. ;o)
« Reply #7 on: May 14, 2012, 01:10:09 pm »
That's what I was asking because I have not personally seen it- motorcycle 10W50 oil.
"Well, Mr. Carpetbagger. We got somethin' in this territory called the Missouri boat ride."   Josey Wales

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Offline Bob Wessner

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Re: Oil Question... no, not that kind of question. ;o)
« Reply #8 on: May 14, 2012, 01:18:59 pm »
10/50 will have additives to make it such a wide multigrade and will contain those slippery molecules we dont like for wet clutches.

Apparently not necessarily so.

http://motorcycle.chaparral-racing.com/racing/10w50

So, I guess I am back to the crux of my question about 10w vs. 20w.  ???
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Offline Deltarider

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Re: Oil Question... no, not that kind of question. ;o)
« Reply #9 on: May 14, 2012, 01:36:41 pm »
You don't need 50 and unless you do many starts below 0 (Celsius) you don't need 10.
Honda recommended 10W-40 just to cover all possible use. Most of us will be fine with 15W-40. Honda France even recommended 20W-40 back then, an even stronger oil.
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Offline TwoTired

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Re: Oil Question... no, not that kind of question. ;o)
« Reply #10 on: May 14, 2012, 01:57:32 pm »
10W-50
The first number is what base stock was used in the formulation without the additives.

So, a 20W number will never attain the flow characteristics when cold as 10W.

The 40 or 50 number is what the oil behaves as when it gets hot.  It is still as thin as the base number would be at that temp, but it lubricates and gives a film strength as a base stock of that thicker viscosity would.

None of this speaks toward the oil's resistance to breakdown from the heat experienced.  At some threshold the, additives or viscosity modifiers break down and stop performing.  Which means the base stock is providing the viscosity index.  However, that base stock can also break down with heat, carbonize, and stop giving lubrication as needed.

It is not easy to find the temperature breakdown index of the chosen oil.  However, a true synthetic oil has a much tighter control of the molecules used in it's construction with little impurities.  Refined oil always has some impurities, sulfur, ash, etc.  A true synthetic won't have those, yielding a uniform molecule size and a more predictable and higher temperature withstand before molecular breakdown, and none of the impurities to scape metal as the oil breaks down.

What I do.  I follow what Honda recommended 10W-40 for all weather conditions.  But, I do occasionally get into hot weather and traffic (low air flow) which will damage the oil.  As a trade off between economy and performance, I'll use a synthetic blend oil so as to retain at least some portion of the oil that can maintain lubrication at those high temperatures.  When the clutch starts to drag enough that shifting starts to get stiffer, that signals me that I must change the oil to restore full properties.  I still try to maintain normal oil change intervals, but those intervals get shorter when I actually do encounter high engine heat.

If money was no object, I'd just use full synthetic PAO oil  Which is not "refined to an approximation of synthetic standards" but a true synthetic, manufactured oil.

Of all my owner's manuals, only the 72 CB500 makes mention of 20W-50 oil.  From 74 onward the recommendation is 10W-40.
I can only speculate why the change, as perhaps the oils got better, or they had more warranty claims with 20W50 oil use?  I don't have Honda internal thinking on the matter.

I've been swayed by urban folklore to use 20W50 on some of my bikes.  I can't say there was detriment or benefit from doing so.
But, use of an oil outside of recommendation is easily defined as experimentation.  Since I don't care to take the engine apart any earlier than necessary, I'll stick with the viscosity recommendation of the manufacturer, and try to select an oil that can survive high heat.  I'm aware of no certain detriment for doing so.

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