10W-40 vs 20W-50

[cablerum]

Hi all, so my Katana 750 calls for 10W-40 oil, which is what I am currently using. I am using Amsoil snythetic oil & Amsoil filter. I am just wondering if anyone is running 20W-50. I know many with V twins running that grade & just thinking it may add extra protection with high RPM & heat since the bike is air/oil cooled. I know it may affect gas mileage slightly but apart from that, any pros or cons or just plain not recommended. Thanks!

[cnyoung]

10w40 is the right oil 20/50 is for v twinns realy dont put 20/50 in there, i run 15/w40 or 10/w40

[hardlydangerous]

If you were racing this engine a 20w-50 would be perfect.

people actually know so little about oil they just take what is in the owners manual as the way it MUST BE. thats not so. maybe it was back in 86 when they developed this engine but not today, not with todays oils. If people would do a lil more research so many oil arguments on internet forums would disapear.

It is not that a 20w-50 was not recommended, its is simply stated the a 10w-40 was a better grade to use for all purpose riding. look in the owners manual and you will see in hot climates a 15w-40 -20w-50 can be used

way back when these engines were designed synthetic were not widely used. the differences between a 10w-40 and 20w-50 in conventional oils were huge.

Todays synthetics have MUCH lower pour points then regular oils did and still do and higher breakdown and flash points. So they cover a much wider range.
A 10w-40 was recommended because these bikes run in all types of conditions and all kinds of temps. However todays synthetics can do far more then the oils of 20+ years ago.

That being said if you are using a synbthetic oil like amsoil where the pour point of a 20w-50 is lower then that of a conventional 10w-40 with better high temp sability and protection there is no reason NOT to use a group IV-V20w-50 synthetic.

Every 4 stroke race engine I have ever built ran on 20w-50.

if you are not using a synthetic, then I would say NO do not use a 50w oil because the cold start damage from lack of oil and oil flow will case premature engine wear and extra load on the pump.

[DClark]

20-50 is fine, I think the manual says the same too. I have read literature from oil companies that 20-50 can give smoother, quieter operation than 10-40. I think this is because as it is thicker, it will stick more to cases and what not, muffling a bit better.
A 20-50 is better for air cooled motors because there is more clearance between the rings. All is not rosy though in the world of 20-50 as the drawbacks are:
1) less hp/mpg. SInce the stuff has higher viscosity, it is harder for parts to move in it
2) The higher viscosity will also slightly raise operation temps from fluid friction.
The bigger question with modern synthetics is- can you run 5-30? Doing so will give more power. I have a mixture of 5-30 and 5-40 in my bike right now.

[steves]

I think the harder problem would be finding JASO-MA oil in 20-50. I don't recall ever seeing that weight at any of the stores I frequent. Maybe rotella?

[cablerum]

I think the harder problem would be finding JASO-MA oil in 20-50. I don't recall ever seeing that weight at any of the stores I frequent. Maybe rotella?

Thanks for the replies from everyone, I did see the 20w-50 in the manual but was unsure since 10W-40 was the recommended. Amsoil makes a 20W-50 motorcycle oil, only costs a few cents more then the 10W-40.

[Steveb]

I know many with V twins running that grade & just thinking it may add extra protection with high RPM & heat since the bike is air/oil cooled. I know it may affect gas mileage slightly but apart from that, any pros or cons or just plain not recommended. Thanks!

How do you feel the extra protection will be provided?

Film thickness is, for the most part, a function of bearing clearance.
Unless you plan to run the engine "loose"...

Amsoil will provide more protection than a street engine will probably ever need.

[cablerum]

How do you feel the extra protection will be provided?

Film thickness is, for the most part, a function of bearing clearance.
Unless you plan to run the engine "loose"...

Amsoil will provide more protection than a street engine will probably ever need.

You make a good poing with the film thickness, I just assumed (never assume) that the higher viscosity oil would provide more protection when it comes to thermal break down, although I know the 10W-40 Amsoil is a superior oil.

[Jimmie]

I run mine on 10w-50 (fully synth, JASO MA spec), as I usually start the season early and want good cold start protection (10w). Seems to work fine, but then again, 10w-40 is probably just as good.

[hardlydangerous]

Almost any 20w-50 motorcycle oil is JASO approved.
Amsoil, M1, Motul etc...
viscosity and film strength change with heat and thats why race engines often use 50w or 60w oil.
if your doing a lot of city riding, or high temps for extended amounts of time a 20W-50 will be fine. like I said a synthetic 20W-50 has a lower pour point then a conventional 10w-40 and just slightly higher operating temp viscosity so you wont notice and performance loss or mileage loss with the better quality synthetic

[FloridaKat]

You don't HAVE to choose one OR the other. I run a blend in my GSX650F. Living in Florida, I want the added weight in the summer and run 20W50 (1 qt.) with a balance of 10W40. In winter, I run the pure 10W40. Pure and simple.

[mammut89]

I just found a good deal on Castrol power 1 racing 10-50. This discussion has mostly been on 10-40 vs 20-50.

can anyone settle the use of 10-50 synthetic in norwegian riding season climate ( 5 degrees C - 30 degrees C ) and 4-5 track days ?

[loudnlow7484]

5°C is pretty cold..... I would guess at those temps you'd be better off with something thinner.

[TRPUT]

As long as you are in viscosity range (10/40 or 10/50) the more important factors are the less advertised sheer and pressure ratings of an oil. There is a greater chance that a true JASO synthetic oil will provide correspondingly higher sheer and pressure protection than a dino oil due to the quality of the base and additive package, but not necessarily. Higher viscosity alone does not necessarily equal higher protection.

[scottynoface]

10w50? I can honestly say I've never seen that before...