15W-40 vs 20W-50 oil

[acebars]

I don't see how 15w40 can only be suitable up to 20 Celsius when 10w40 is the standard for most and many aircooled bikes of the 70s..

My CB500t a hot air cooled runner has 10w40 recommended by the manual.

Something wrong with that diagram.

I'm not suggesting 20w50 isn't the best oil, but trying to find out whether or not I can get away with 15w40 in the UK not the warmest climate in the world.

 

[Newagerocker]

There is no degree symbol on the keyboard but it can be had by using the numbers lock then hold down the "alt" key while typing 0176 on the number pad, like so - 64°.

° Thanks °

 

[xjwmx]

trying to find out whether or not I can get away with 15w40 in the UK

The most frequent complaint is that it gives more top end noise. But in my experience with my bike that extra noise goes away once the temperature gets into the 60s or lower. Fahrenheit. Ja wohl.

 

[650Skull]

A real important thing to realize when reading and giving opinions about oil and its worth on a forum like this.......

This is an American site so most information is based on American information and directed to an American populace.

Oil varies from country to country and continent to continent.

I have made the mistake before about basing information given about the XS650 from the gurus, (no disrespect intended or implied), based on American information and have applied it to mine here in Australia and found that some things are different. Some small things but could be very important to the overall running of the bike.

My point is on the oil, Learn about what Viscosity means and how it relates to your situation and combine that with research locally, from your local manufacturers, most will have the relevant information regarding ZDDP and viscosity flows information in their fact sheets.

Note: One thing to remember is the standard for oil rating is a set standard. Some multiple weight oils may be a the top end of their rating, closer to a higher rating and some will be at the bottom end of their rating making a lower rated oil as good.

Higher ZDDP levels also affect the oil Viscosity and if ZDDP is added to oil it could do more harm than good, (Caution to angus67). Their is a myth that all oil companies removed or lowered their ZDDP content to .08 to all oils for environmental purposes, but the truth is the laws only applied to oils, (multiple weight), up to and including 30 weight oils. Some of the multiple weight 40's and higher still have more ZDDP than motorcycle specific oils.

Here is some information on ZDDP and its relation to oils and how the Viscosity flow rate is determined. I have included some technical data and the variations on weight aand ZDDP levels on one make of oil,

Modern Oils in Older Engines. From the Jaguar Driver Club

Understanding the SAE Motor Oil Viscosity Standard

ZINC MYTHS AND LEGENDS 2010 UPDATE Although this is from an oil company it explains the various countries requirements and a lot of the myths that relate to this discussion.


15W/40; semi synthetic car light duty diesel oil,

15W/40; heavy duty diesel oil,

20W/50; mineral oil for older cars

20W/50;motorcycle specific

I don't see how 15w40 can only be suitable up to 20 Celsius when 10w40 is the standard for most and many aircooled bikes of the 70s..

My CB500t a hot air cooled runner has 10w40 recommended by the manual.

Something wrong with that diagram.

I'm not suggesting 20w50 isn't the best oil, but trying to find out whether or not I can get away with 15w40 in the UK not the warmest climate in the world.

I did post the answers in the information above.........Read the second link.........

Basicly it is the flow rate at 2 predetermined temperatures (one high and one low) through a predetermined hole and depending on ZDDP levels and other factors then even a good 20W/40 can be as good as a poor 20W/50. or a poor 20W/40 could be as good as a good 15W/40.

That's why it is important to do the research on any oil that you intend to use.

 

[angus67]

I did post the answers in the information above.........Read the second link.........

Basicly it is the flow rate at 2 predetermined temperatures (one high and one low) through a predetermined hole and depending on ZDDP levels and other factors then even a good 20W/40 can be as good as a poor 20W/50. or a poor 20W/40 could be as good as a good 15W/40.

That's why it is important to do the research on any oil that you intend to use.

Thank you for those links, skull. I will dig deeper before putting any in my 650. Car guys have been doing it for years to protect lifters and rockers, valve tips on non-roller engines. prevents galling.

 

[Brian G]

I do so enjoy these oil threads

Just to stir things up a little more, I use a house brand (Canadian Tire) fully synthetic 5W50 in everything but the Kawasaki triple. The Hondas have wet clutches and the BSA a dry clutch and I haven't detected any slippage. I like the idea that the oil gets pumped throughout the engine quickly and as the engine warms, the viscosity index moves into the upper ranges anyway. I used to use straight 50 in my other BSAs of the same year and have had no oil related issues with the triple using the 5-50 synthetic in the eight years I've owned it. This choice got a 'thumbs up' from a couple of the knowlegeable members of the Honda and BSA forums as well.

I'm about to do the first oil change on the Yamaha. Notwithstanding the issue of plain vs roller bearings, is there any reason I shouldn't continue with this same oil?

Thanks and Regards,

 

[weaselbeak]

Our local hotrodder when I was in high school, locally famous for his 62 Vette, a 409 Belair, and 55 Chevy, all set up for drag,ran a straight 10 weight oil. He was badass in the drag circles here, and did not lose engines. The 55, with a wildly lumpy cam and serious compression, was his daily driver year round.

 

[Scrambled]

I do so enjoy these oil threads

Just to stir things up a little more, I use a house brand (Canadian Tire) fully synthetic 5W50 in everything but the Kawasaki triple. The Hondas have wet clutches and the BSA a dry clutch and I haven't detected any slippage. I like the idea that the oil gets pumped throughout the engine quickly and as the engine warms, the viscosity index moves into the upper ranges anyway. I used to use straight 50 in my other BSAs of the same year and have had no oil related issues with the triple using the 5-50 synthetic in the eight years I've owned it. This choice got a 'thumbs up' from a couple of the knowlegeable members of the Honda and BSA forums as well.

I'm about to do the first oil change on the Yamaha. Notwithstanding the issue of plain vs roller bearings, is there any reason I shouldn't continue with this same oil?

Thanks and Regards,

You should read the posts by pamcopete about synthetic oil . My bad experience with synthetics and vintage bikes is clutch slippage and wear . I use Castrol 20w50 regular car oil ( much cheaper than motorcycle oil ) in the summer and 10w40 if I ride in the cold months ( below freezing , which I hardly ever do anymore ) .

 

[5twins]

I can't justify the cost of synthetic or fancy motorcycle oil since I dump it about every 1000 miles. I think that's the key here, no matter what oil you use - change it often.

 

[weaselbeak]

I can't justify the cost of synthetic or fancy motorcycle oil since I dump it about every 1000 miles. I think that's the key here, no matter what oil you use - change it often.

X2. This never changes

 

[Biggles]

There's an amazing amount of disinformation about oils out there like "need 50 because 40 is too thin" and "never use 15w always use 20W because 15 is too thin"

The forum that I find most reliable is called bobistheoilguy. It's mostly car engine liquid cooled technology based but most info is reliable.

If you do their oil university program you will learn that most non-synthetic oils are too thick at start-up for our engines at any normal ambient temperature (where most of the wear occurs). Also that its the dynamic viscosity at the operating temperature of the engine that's crucial (about 30cs for most engines) for wear protection at whilst running. Look further and get the info about flow/pressure tradeoff's. Then get the material spec like 650Skull reproduced and find the oil that fits. For my money in Oz that's Penrite Synthetic 5w-40 Jaso MA approved.

The idea is that it has the lowest viscosity (about 10cs) at 30 deg C (my ambient temp here in Darwin) and maintains its viscosity of 34cs at 100 deg C (possibly the temp of the piston ring interface is higher than this......)

My 2 bob's worth

Biggles

XS650 2F in a lot of pieces.....