I've noticed in the forums that 15w and 20w50 oils are very popular. My manual calls for 10w30 or 20w40, but the previous owner ran 20w50 in the bike. What are the pros and cons of running a thicker oil?
50 weight oil
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The 15w-40 and 5w-40 synthetics are just so easy to come by. And there are so many people using Rotella on other bike forums, it's an easy way to insure you're not going to have problems.
the x-50 oils might be better, but there isn't a large user community of them.
the x-50 oils might be better, but there isn't a large user community of them.
Advantages to thicker oil:
- Thicker films
- Better ring sealing
- Higher oil pressure (until you hit the pump's bypass limit)
- Can run at higher temps without becoming too thin
- If it shears or becomes diluted by fuel, it'll still be pretty thick
Disadvantages to thicker oil:
- More drag on moving parts: less power & fuel economy
- More prone to aeration; could compromise lubrication and cause oil consumption via excess crankcase pressure
- Less efficient cooling; more hot spots
- Won't flow as easily on a cold start
This is all-else-equal, of course. It's entirely possible for a good xw-50 to be better in every way than a bad xw-40. But I'm assuming you wouldn't make that comparison.
A good way to think about viscosity is that you want it to be "as thin as possible, as thick as necessary."
- Thicker films
- Better ring sealing
- Higher oil pressure (until you hit the pump's bypass limit)
- Can run at higher temps without becoming too thin
- If it shears or becomes diluted by fuel, it'll still be pretty thick
Disadvantages to thicker oil:
- More drag on moving parts: less power & fuel economy
- More prone to aeration; could compromise lubrication and cause oil consumption via excess crankcase pressure
- Less efficient cooling; more hot spots
- Won't flow as easily on a cold start
This is all-else-equal, of course. It's entirely possible for a good xw-50 to be better in every way than a bad xw-40. But I'm assuming you wouldn't make that comparison.
A good way to think about viscosity is that you want it to be "as thin as possible, as thick as necessary."
Originally Posted By: outoforder
I've noticed in the forums that 15w and 20w50 oils are very popular. My manual calls for 10w30 or 20w40, but the previous owner ran 20w50 in the bike. What are the pros and cons of running a thicker oil?
Yamaha, per chance?
I ran 15w50 in my XJ550 for many years. (spec'd at 20w40)
I've noticed in the forums that 15w and 20w50 oils are very popular. My manual calls for 10w30 or 20w40, but the previous owner ran 20w50 in the bike. What are the pros and cons of running a thicker oil?
Yamaha, per chance?
I ran 15w50 in my XJ550 for many years. (spec'd at 20w40)
The 15/50 probably sheared down to a 40 wt oil , so you were still in spec for what was called for.,,
My Bonneville is living on 15W-40 Rotella right now. When I took it in for the 500 mile service the dealer used Triumph oil which I understand is 15W-50 Mobil 1 4T. I haven't been able to find that any where but the dealer for about $15 a quart. In my upcoming change I will be using 20w-50 Mobil 1 V-Twin. The summers can be brutal on air cooled engines in Georgia.
outoforder,
have you looked in your manual to see what outdoor temp ranges require what weight oil for your bike?
i've even posted what mine looks like.
have you looked in your manual to see what outdoor temp ranges require what weight oil for your bike?
i've even posted what mine looks like.
Originally Posted By: OilNerd
Originally Posted By: outoforder
I've noticed in the forums that 15w and 20w50 oils are very popular. My manual calls for 10w30 or 20w40, but the previous owner ran 20w50 in the bike. What are the pros and cons of running a thicker oil?
Yamaha, per chance?
I ran 15w50 in my XJ550 for many years. (spec'd at 20w40)
Of course its a Yammer Hammer. Who else made a 20w40? I'll go as far as to say its blue.
They changed their 10w30/20w40 spec to a 10w40/20w50 in recent years.. IIm also going to call it a sportibke with an R in the name.
Originally Posted By: outoforder
I've noticed in the forums that 15w and 20w50 oils are very popular. My manual calls for 10w30 or 20w40, but the previous owner ran 20w50 in the bike. What are the pros and cons of running a thicker oil?
Yamaha, per chance?
I ran 15w50 in my XJ550 for many years. (spec'd at 20w40)
Of course its a Yammer Hammer. Who else made a 20w40? I'll go as far as to say its blue.
They changed their 10w30/20w40 spec to a 10w40/20w50 in recent years.. IIm also going to call it a sportibke with an R in the name.
outoforder
Air cooled or water cooled engine? Air-cooled oil cooler?
First, look in your owner's manual for the probably long list of recommended oil viscosities. In an air cooled engine, I'd use the xW-50 weight oil for weather generally above 80°. For a water cooled engine I'd use the xW-50 oil for weather generally above 90°. My water cooled V-Strom has the typical Japanese recommendation for 10W-40 oil, but the owner's manual has a chart showing that 20W-50 is good from +14°F to off-the-chart-hot. 15W-50 is good down to +5°F. I run 5W-40 and would use 20W-50 if I rode in very hot summer areas (humidity doesn't count). I want an oil that protects the hottest points inside the engine.
Air cooled or water cooled engine? Air-cooled oil cooler?
First, look in your owner's manual for the probably long list of recommended oil viscosities. In an air cooled engine, I'd use the xW-50 weight oil for weather generally above 80°. For a water cooled engine I'd use the xW-50 oil for weather generally above 90°. My water cooled V-Strom has the typical Japanese recommendation for 10W-40 oil, but the owner's manual has a chart showing that 20W-50 is good from +14°F to off-the-chart-hot. 15W-50 is good down to +5°F. I run 5W-40 and would use 20W-50 if I rode in very hot summer areas (humidity doesn't count). I want an oil that protects the hottest points inside the engine.
A lot of manuals will have a chart with minimum and maximum air temperature range and then a recommended weight.
Have another look at the manual. Then determine what air temperature your bike will run.
The reason the manufacturers do this is they sell their vehicles to all different parts of the world that have varying temperatures.
A 20w50 oil would be perfect for Florida but a 20w40 would be deadly for an engine in the colder parts of the US.
Have another look at the manual. Then determine what air temperature your bike will run.
The reason the manufacturers do this is they sell their vehicles to all different parts of the world that have varying temperatures.
A 20w50 oil would be perfect for Florida but a 20w40 would be deadly for an engine in the colder parts of the US.
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