Ok lets talk viscosity

[YamaDuck]

Lets talk a little about viscosity. As everyone can agree that we as a group cannot agree on which motor oil to use. As ststed in my owners manual if I don't use Yamalube I can use any SAE 10W30 motor oil without friction additives. So I take that to mean Yamaha does recommend car or automotive motor oil. So now that brings me to this question. If Yamaha recommends SAE 10W30 what happens if I put 5W40 or 15W40 or even 20W50 in it? Yamaha doesn't recommend 5W40 but 10W30 is within the range of 5W40 so is it alright? Isn't 5W40 a little to then on hot days and a little to thick on cold days? I don't remember reading anything about what climate you live in so I assume Yamaha took that into consideration when they recommend any SAE 10W30 oil? Let the fun begin and hopefully we will all learn something from this.

Harry:puzzled:

[MiCarl]

As ststed in my owners manual if I don't use Yamalube I can use any SAE 10W30 motor oil without friction additives.

 

On my 1st gen it specifies 10W30 below 60degF and 20W40 above 40degF.

 

I run 15W40 all the time. If I lived down South I'd be really tempted to run 20W50 in the summer.

 

What do all those numbers theoretically mean?

 

A 10W30 has the viscosity of a 10 weight base oil cold and the viscosity of a 30 weight base oil hot. (I believe cold=32F and hot=212F, but don't hold me to it).

 

A 10W30 is a 10 weight base oil with additives that enhance it's high temperature viscosity. With use, those additives break down so that 10W30 becomes 10W25, 10W20 and eventually just 10W.

 

Synthetic oils are a special case. They have a broader viscosity range with less (or no) additives.

[flb_78]

First, one needs to understand the numbers.

 

The first number 0W, 5W, 10W, 15W, 20W stand for their "winter" weight or cold weight.

 

The second number 20, 30, 40, 50 is the weight of the oil at operating temperatures.

 

http://auto.howstuffworks.com/fuel-efficiency/fuel-consumption/question1641.htm

 

Multi-weight oils (such as 10W-30) are a new invention made possible by adding polymers to oil. The polymers allow the oil to have different weights at different temperatures. The first number indicates the viscosity of the oil at a cold temperature, while the second number indicates the viscosity at operating temperature.

The first number isn't as important as the second number for most folks. Folks who commonly ride is very cold temps will want a lower first number for better oil flow at cold startup.

 

The second number is the number to look at. At operating temperatures, a 10W40 and a 15W40 oil will flow the same in theory.

 

I don't have my owner's manual in front of me, but I believe Yamaha recommends a non-friction modified 10W30 or 20W40 depending on riding conditions.

 

A 5W-40 oil should be more then suffice for these engines.

 

It'd be interesting if someone who has installed the gauges to test a 5W40 oil and a 20W50 oil to see the difference in oil pressures at different temperatures.

Edited September 7, 2009 by flb_78

[SilvrT]

I would suggest that BOTH numbers are important.

 

For the most part, 10w30 or 10w40 is fine just about anywhere, anytime with a couple exceptions...

 

If you live in the north (Canada) and you ride in the winter, use something that starts with 5

 

If you live in the south (Texas) and you ride in the summer, use something that ends with 50.

 

Simple.

[jlh3rd]

10w-30 is not within the range of 5w-40........it doesn't work that way......we're not talking about ranges between oil ratings, we're talking the range specified by the manufacturerfor the oil for the motor in question.......so...at operating temp ( tested at 210 degrees) , if the manufacturer says they want an oil with the last number of 40, then the 5w-30 is not recommended because it will be thinner than the 40w at temp. if the last number is 50, then it would be too thick...

also , at cold temps , they want the oil to flow as thin as a 5w, so the 10 w is too thick ......if the first number is a "0", then it would be too thin

 

i'm just talking engineers and manufacturer's specs......and warranty......anyone can do as they please.....but if the manual says the oil should be a specific weight or range, and you run a different one than specified, and your motor develops a problem.....they could refuse to honor a warranty........they can tell what weight of oil you run............

course, i could just change my oil before i brought it in........i think.....

[Condor]

Hmmm... I'd always been taught that a 20-50 had the viscosity of 50wt that flowed like 20. Same thing on 10-30 or 15-40, etc.

[jlh3rd]

my understanding is that a 20w-50 means that the oil will get no thinner than a 50 w oil at running temp. ........and no thicker than a 20 w oil at colder temps......supposedly the test for the high temp. is measured at 210 F.......i don't know what temp the cold rating is measured at......

the oil will actually change it's viscosity within it's rating based on temps.

that's always been the way i've understood it.......

[GaryZ]

I will put a little wood on this fire . . .

 

Many years ago a motorcycle magazine tested a popular myth. Remember, those were the days when almost all bikes were air cooled. The myth (and practice) was to not use factory recommended 10W40 motor oil and use 20W50. Does this sound like our discussion?

 

The test was to add an oil temp gauge to the test bike (don't remember the brand, I think it was a twin) and make a brisk run up a local mountain on a summer day while monitoring the temp.

 

The results surprised everyone. The 20W50 ran hotter.

 

The magazine conclusion: Maybe we should run the recommended weight oil.

 

This conclusion especially is important to me because my VR runs very hot when the air temp is around 100 degrees. I do not want the oil adding more heat . . .

[jlh3rd]

i'm not surprised.....no matter how much we think that a designer/manufacturer did a bad job......bottom line is that they do a good job of R and D and know the clearance tolerances of their motors........and what grades of oil should be used......

and over the years manufacturing processes have gotten better, tolerances tighter , oils better....and sometimes old rules just don't apply anymore

[5bikes]

You may be amazed...

60+ psi engine cold

Never over 25 psi, even at 80 mph.

Idle (1k) 3-6 psi is all!!

This is with 15w-45 (mix of 10W-40 and 20W-50, (same brand & type)

Oil 1/2 way up sight glass.

 

I ALSO have oil temp gauge. Usually about 140-160 F. unless I'm idling a long time. Saw 180 once

Edited September 9, 2009 by 5bikes
More info

[jlh3rd]

pressures are similar to mine when i'm in 5th gear,except i see 28psi....if i cruise around in 4th, i see psi's of 35+, and if i run the revs up i will see 50s

[buddy]

Well my Venture & Wing take the same oil filter , So I switch over to Rotella-T 15w40 for both bikes. same filter & oil so there is no problems in keeping up which one has what. Both are doing great on the oil so why worry...

[Ndiaz]

Ever since I bought my 88 Venture Royale a year ago, I've been using Castrol 10W-40 motorcycle-specific oil, available at Pep Boys. NOT a synthetic.

 

I use it year round, in all temperatures. No oil consumption that I've noticed. It stays put in the sight glass every time I check the level after a run, on the centerstand, in my garage. Even in the heat of August, the oil level remains the same. No noises, nothing.

 

No problems whatsoever. I've ridden the Venture now about 11,000 miles, with no lubrication problems.

 

I'm staying with what works. I change the oil and filter every 2,500 to 3,000 miles.

 

Nick Diaz

Middletown, MD