Oil weight question for MarkC

[sanoke]

Thought I'd make this public so everyone could benefit from Mark's answer.

Two of my bikes are air cooled Yamahas (XJ550, XS850). Both are spec'd to use 20w-40 Yamalube. I decided I wanted to try using Castrol GTX instead to save some money so this past summer I've been running 20w-50 in both. I'm very pleased with the results. Good shifting, very little valve wear, etc. However, it's now coming into the cooler time of the year here and last winter I noticed both bikes were sluggish to start with 20w-40. My thinking is to switch both to 10w-40 for the winter months and hopefully things will be ok. The temp here from now until spring won't get much higher than the 60's so I'm thinking the 10w-40 should work ok.

So Mark, what do you think of my reasoning here?

Happy Trails!
sanoke

[SHADOW 1100T]

Well I'm not Mark but you won't be the first to run that weight oil when it get a little cold, I do it and have been doing it for some time. The oil pump will maintain a given pressure and is actually capable of very Hi pressures but the bypass valve keeps it at the factory level so in essence your passing more oil at a given RPM than with the 20wt because it's a little thinner

[sanoke]

Originally Posted by SHADOW 1100T

Well I'm not Mark but you won't be the first to run that weight oil when it get a little cold, I do it and have been doing it for some time. The oil pump will maintain a given pressure and is actually capable of very Hi pressures but the bypass valve keeps it at the factory level so in essence your passing more oil at a given RPM than with the 20wt because it's a little thinner

Thanks Ted. That makes sense to me so I think I'll go ahead and try it.

[PaleRider1966]

Originally Posted by sanoke

......very little valve wear....

That's an interesting observation. Exactly how did you measure that parameter?

[sanoke]

Originally Posted by PaleRider1966

That's an interesting observation. Exactly how did you measure that parameter?

The Yamahas use shims to adjust the valves. I check both bikes every 10,000 miles. I put over 10,000 miles on the XJ550 with the 20w-50 oil and I didn't have to change any of the shims as the clearances were all still in spec.

[PaleRider1966]

Makes sense!

[SHADOW 1100T]

Actually the oil has nothing to do with having adjust the valves, O sure you have to have oil for them to work but it has nothing to do with adjusting, the only thing that causes a need to adjust them is them wearing/pounding in to the valve seats, as they do this the clearence closes up and the shims need to be changed to maintain proper clearence, some of the newer bikes can and do go a LONG time before the first adjustment is needed, my ST1100 is at 78,000 and hasn't been touched, checked yes but it's still OEM.

[MarkC]

Originally Posted by sanoke

Thought I'd make this public so everyone could benefit from Mark's answer.

Two of my bikes are air cooled Yamahas (XJ550, XS850). Both are spec'd to use 20w-40 Yamalube. I decided I wanted to try using Castrol GTX instead to save some money so this past summer I've been running 20w-50 in both. I'm very pleased with the results. Good shifting, very little valve wear, etc. However, it's now coming into the cooler time of the year here and last winter I noticed both bikes were sluggish to start with 20w-40. My thinking is to switch both to 10w-40 for the winter months and hopefully things will be ok. The temp here from now until spring won't get much higher than the 60's so I'm thinking the 10w-40 should work ok.

So Mark, what do you think of my reasoning here?

Happy Trails!
sanoke

I started to answer this last night but I had a power outage before I could post what I had done

Anyway, its not that uncommon for people to run a summer oil and then a winter oil, IF! your going to be riding in pretty cold temps. Your reasoning is good! And the 10W-40 I would think would be fine.

Next!
I'm not a fan of Castrol GTX, yes many people like the oil, so I guess its a personal thing. Keep in mind that when you go from a 10W-40 to a 20W-50 you will notice a performance loss as well. But using the two weights of oil shouldn't really hurt anything.

Now this is something you didn't ask
I don't ride in the COLD so I just use one viscosity of oil in my motorcycle. But! If I was to use two different grades of oil and a non motorcycle specific oil I would look REAL hard at these two oils,

Shell Rotella-T 10W-30 (for winter) and
Shell Rotella-T 15W-40 (for summer)

There is just enough offset in the viscosity range for the climate difference, but not as much of a swing as 10W-40 vs 20W-50. That's a big enough jump that you will more than likely notice a performance difference between the two oils.

MarkC

[sanoke]

Originally Posted by MarkC

I started to answer this last night but I had a power outage before I could post what I had done

Anyway, its not that uncommon for people to run a summer oil and then a winter oil, IF! your going to be riding in pretty cold temps. Your reasoning is good! And the 10W-40 I would think would be fine.

Next!
I'm not a fan of Castrol GTX, yes many people like the oil, so I guess its a personal thing. Keep in mind that when you go from a 10W-40 to a 20W-50 you will notice a performance loss as well. But using the two weights of oil shouldn't really hurt anything.

Now this is something you didn't ask
I don't ride in the COLD so I just use one viscosity of oil in my motorcycle. But! If I was to use two different grades of oil and a non motorcycle specific oil I would look REAL hard at these two oils,

Shell Rotella-T 10W-30 (for winter) and
Shell Rotella-T 15W-40 (for summer)

There is just enough offset in the viscosity range for the climate difference, but not as much of a swing as 10W-40 vs 20W-50. That's a big enough jump that you will more than likely notice a performance difference between the two oils.

MarkC

Thanks Mark. I just bought a case of 10w-40 so I think that's what I'll use this winter. I do think i'll try switching to Rotella net summer and see how that works. Just out of curiosity, why are you not a fan of Castrol GTX?

[sanoke]

Originally Posted by SHADOW 1100T

Actually the oil has nothing to do with having adjust the valves, O sure you have to have oil for them to work but it has nothing to do with adjusting, the only thing that causes a need to adjust them is them wearing/pounding in to the valve seats, as they do this the clearence closes up and the shims need to be changed to maintain proper clearence, some of the newer bikes can and do go a LONG time before the first adjustment is needed, my ST1100 is at 78,000 and hasn't been touched, checked yes but it's still OEM.

My assumption was that if the oil broke down then there would be wear on the cam lobes and valve shims that would loosen the valve clearance. The pounding of the valves on the seats would tighten the clearance as the valve would move down into the seat further.