Bike manual calls for a 10w-40, can I use a 5w-40?

[Booki]

Hey all,

I have a 2013 WR250F and a 2006 SV650N, both bikes call for a 10w-40 oil, but thinking that a lower Winter rating would be better for my engines.

From what I know about oil, all that will be different will be the "cold" start rating. Once warm they should be the same viscosity as recommended by the manufacture, but can having a lower Winter rating cause damage to a motor? Will it not "stick/retain" as well to the bearings and other components due to being a thinner winter grade?

Are there any drawbacks or concerns to running a lower Winter grade then recommended by the manufacture?

Does having a lower viscosity indicate a "thinner" oil in terms of its physical properties, or does it just flow better?

 

[eljefino]

yup

 

[BigCahuna]

I always stick to the wt oils the mfgr recommends. Not the brands they recommend. But if they don't say to use 5/40, I wouldn't.,,,

 

[Oli20]

I use 5w-40 in my ATV that calls for 10w-40 in most applications. T6 and I know a lot of other people that swear by it. The ATV manual allows all the way down to 0w-30 based on ambient temp, so a 5w can't cause an issue imho.

 

[LoneRanger]

It may shear down a little quicker than 10W since it uses a thinner base with more Viscosity Index Improvers to widen the Viscosity Index. Unless you intend to operate in very cold temps I would stick with the manufacturer's recommendation of 10W40.

 

[bubbatime]

The only issue is that 5W40 tends to shear down to a 30 weight fairly quickly. So don't use it for long intervals. Also, make sure the oil says MA/MA2 on the back indicating it is safe for wet clutch use. In America Rotella 5W40 is the only one I'm aware of.

 

[UltrafanUK]

Originally Posted By: BigCahuna
I always stick to the wt oils the mfgr recommends. Not the brands they recommend. But if they don't say to use 5/40, I wouldn't.,,,


It depends how old the vehicle is as 5w40 might not have been around or was too expensive an option in the old days.

If the manufacturer still exists and has active dealerships, they do update the recommended oil specs.

My own old 1.9 TDI was OEM spec for a 10w40, then an 0w40 and finally a 5w40, even though some UK dealerships stuck with the 10w40 for economic reasons.

 

[OneEyeJack]

If you have the slightest doubt you could try the exact viscosity specified.

 

[CT8]

There would be probably no draw backs to using s lower cold grade but why?

 

[Robenstein]

Unless you are riding in cold weather, you won't likely notice the difference in cold viscosity. You will however notice the shearing happens quicker in a shared sump system.

 

[donnyj08]

Originally Posted By: bubbatime
The only issue is that 5W40 tends to shear down to a 30 weight fairly quickly. So don't use it for long intervals. Also, make sure the oil says MA/MA2 on the back indicating it is safe for wet clutch use. In America Rotella 5W40 is the only one I'm aware of.


Agree shear will be an issue. Besides T6 motul, Maxima, and, ENI make 5w40 MC oils. They are going to be online order only most likely. You will have a better selection of you stick with a 10w40 oil.

 

[Booki]

I would like to fight against the shearing, especially in the WR, being carby'd, small sump and lots of fuel dilution along with shared gearbox duties.

Looks like I will be sticking with a 10w-40.

Only reason is there is a great deal going on a full synth 5w-40 (Valvoline Synpower, ends up being $25 for 5L) car oil that will work with wet clutches,

If anybody knows any other oils that are cheaper alternative then "motorcycle" designed oils, let me know.

Based in Australia, plus another bonus would be just to stock up on one type. I could use it in all my vehicles, cars and bikes.

 

[Robenstein]

many people use 15w40 HDEO "diesel oils" with good success. They often will be more resistant to shear versus a 10w40. And given the warm climate you live in, the cold start flow should still be good.