Recommended oil viscosity

'13 vfr 1200.

I'm about to do my 600 mile service. Went to buy some oil from the dealership and they gave me 10–40 even though the bike calls for 10–30.
Should I go ahead and use 10–40, or return it and get 10–30?

Thanks

 

Um, what he said!

 

Derstuka is correct, shearing is when oil molecules break down under high stress, as he said pure synthetics (there are alot of synthetic blends) do not have the viscosity polymers that don't break down. I run Amsoil pure synthetic. Mobil 1 is good too. Stick to "Motorcycle" oil which do not have friction modifiers, which may bother wet clutch.

 

INDE_Andy, my manual (1999 VFR800) Shows about 4 different viscosities with a temperature chart showing where each viscosity is acceptable. I don't have it in front of me but I think they also list 20W50 in addition to 10w30, 10w40. Those viscosities are a wide range. Which leads me to ask if you got the spec from your manual?

Caveaut I am new to motorcycles, but in the car world these two oils are pretty much considered the same. The reason is that a large portion of engine wear occurs at startup because the engine is dry. and the weight at a cooler temperature is similar, and they both build pressure at startup at a similar rate (maybe not identical.)

As someone said this can be a hotly contested but my two cents would be that a hard recommendation of 10W30 over 10W40 would be due only to the EPA influence, as a slightly lighter oil would take less energy to pump and would provide slightly (if noticeable) better gas mileage. The EPA does rule the roost sometimes, even over physics itself.

 

[video=youtube;HwO7eOO-bNE]http://www.youtube.com/watch?v=HwO7eOO-bNE&feature=player_embedded[/video]

This is all you need to know!

I use Amsoil 10W-40.

 

As was mentioned above, you failed to address the shear factor of motorcycle engines and its effect on (conventional) multi-viscosity oil. 10w-40 is one of the worst choices.

Drawbacks of Viscosity Improving additives
Multi-grade motor oils perform a great service not being too thick at cold startup to prevent engine wear by providing more instantaneous oil flow to critical engine parts. However, there is a draw back. These additives shear back in high heat or during high shear force operation and break down causing some sludging. What's worse is once the additive begins to be depleted the motor oil no long resists thinning so now you have a thinner motor oil at 210 degrees. Your 10W-30 motor oil can easily become a 10W-20 or even a SAE 10 (10W-10) motor oil. I don't have to tell you why that is bad. The more VI additives the worse the problem which is why auto manufacturers decided to steer car owners away from motor oils loaded with VI additives like the 10W-40 and 20W-50 viscosities.
The less change a motor oil has from high to low temperatures gives it a high Viscosity Index. Synthetic motor oils that are made from Group IV (4) PAO base stocks have Viscosity Indexes of more than 150 because they are manufactured to be a lubricant and don't have the paraffin that causes the thickening as they cool. But petroleum based motor oils (Group I (1) & II (2)) usually have Viscosity Indexes of less than 140 because they tend to thicken more at the colder temperature due to the paraffin despite the addition of Viscosity Improving additives. The higher the Viscosity Index number the less thinning and thickening the motor oil has. In other words, high number good, low number bad. Low numbers thicken more as they cool and thin more hot. You see these Viscosity Index ratings posted on data sheets of motor oils provided by the manufacturer.
As already mentioned, VI improving additives can shear back under pressure and high heat conditions leaving the motor oil unable to protect the engine properly under high heat conditions and cause sludging. Also there is a limit to how much viscosity improving additives can be added without affecting the rest of the motor oil's chemistry. Auto manufacturers have moved away from some motor oils that require a lot of viscosity improving additives, like the 10W-40 and 20W-50 motor oils, to blends that require less viscosity additives like the 5W-20, 5W-30 and 10W-30 motor oils. Because stress loads on multi viscosity motor oils can also cause thinning many racers choose to use a straight weight petroleum racing motor oil or a PAO based Synthetic which do not have the VI additives. But only the Group IV (4) PAO based synthetics generally don't need VI additives. Read on to learn why:

http://www.upmpg.com/tech_articles/motoroil_viscosity/

 

Just attaching the oil weight page in the manual for an 86 VFR750 (which from what I've seen in other manuals, seems to be pretty much the exact same or very close even across the different Honda models)

I'm gonna read up on this since I find it interesting what y'all have brought up. I just use the spec that was recommended to me, which is 10W-40. Originally my CBR came with 10W-30 but I heard from a lot of riders to go with 10W-40 cause of how hot it can be in Arizona (we have days where it's 125*F). Was gonna do the same with the VFR700 once I watch and see if she leaks or not and switch to Amsoil just like my CBR runs.

Course I'm completely dumb when it comes to the inner workings of oil, so I could actually be doing the wrong thing.

 

KY works great . Best for the Tight spots

 

Thank you all for the input.

Anything else I should look for on the 600mile service besides oil change ? Im thinking of inspecting the rear diff oil and re -torquing the motor mount bolts. Anyone know to what torque they are supposed to be at?