15W-40 vs 20W-50 oil

[acebars]

Quick query here, I'm in the UK, finding 20w-40 is difficult and expensive for the XS650.

I have found a great deal on Shell Advance 15w-40 mineral motorcycle oil, although I've been reading that many people here use 20w50 motorcycle oil.

Given it's not the warmest country in the world, should I be alright with 15w-40? Am I correct that the advantage of using 20w50 is less engine wear but longer warm up time?

 

[Paulrxs650]

Hi,

I use 20w-50 as its easier to come by than the 40. I prefer it on these older engines. You can get away with 15w-40 too.
Whichever, you go for, make sure you buy oil specifically for motorbikes. Car oils usually have additives to reduce friction that can make wet clutches slip.

 

[acebars]

Yea it's motorcycle oil.

I know I'm over thinking this but I am looking to buy bulk oil to use in the future.

I can get Shell mineral 15w40 very cheaply but told engine wear is reduced with 20w50.

 

[Paulrxs650]

Thats technically correct but dependant on how you ride, mileage, oil change frequency etc etc
If you can get it cheap, Id go for the 15w-40

 

[acebars]

I bought the cheap 15w40 shell advance motorcycle oil. But will have my eye out for bulk 20w50 motorcycle oil in the UK.

 

[5twins]

Many run the 15-40 diesel oil. I tried it but didn't like the increased top end noise that resulted. I never heard the increased wear factor mentioned but if the increased top end noise is any indicator, I guess I can believe it. I went back to the 20-50 and will stick with it.

Yes, car oils can have additives that are bad for a wet clutch. They call them "energy efficient" additives. They make the oil slipperier and supposedly increase mileage. However, those additives are generally only put in the lighter weights, like 30 and below. 40 and 50 weights don't get them, probably because the oil is so thick to begin with, they would do no good. I've used all brands and kinds of 20-50 over the years and never had clutch slipping problems. None were a motorcycle specific oil.

 

[xjwmx]

I use Shell 15-40 when it's consistently about 40F or below and Pennzoil 20-50 when it's above that. One of the big reasons is both are available at every Wallmart, meaning you can get it whenever and wherever. The Pennzoil especially is highly respected oil. You will read about zinc content and which oil has the most, but I've read that all oils have enough.

The Shell doesn't cause any extra noise when the weather is cold, and the Pennzoil is goofy thick when the weather is cold.

 

[retiredgentleman]

20W-50 is the preferred oil for these engines. 15W-40 will work, but your top end will have that nasty tick-tick noise we all dread. When I had motorcycles back in the 1970's and 1980's, I always used 20W-50.

I use motorcycle specific oil, but that is an interesting factoid that 5twins mentioned, using non-motorcycle specific oil.

 

[xjwmx]

I can see the new grads being assigned motorcycle specifics, because it's a small market....

 

[CDNTX650]

i currently run 15-40 in mine....might do the 20-50 when we super got out again in summer. but for spring and fall, the thinner stuff is a bit nicer.

 

[650Skull]

this graph shows that why 20/50 is the oil to use in summer or winter unless the temperature is lower than -10 C

15/40 not in my book

 

[xjwmx]

I go by that chart for the upper end, but good luck starting your xs650 at 25F with 20-50 in it Good luck turning the engine over even.

 

[5twins]

Oh, they'll turn over. I usually take mine out at least once over the winter (if the roads are clear). Granted, the electric leg struggles, but a couple healthy kicks usually do the trick. In fact, I usually kick mine on that 1st start of the day in colder weather, say below 45 or so. It cranks slow even with a good battery. They start easier when you kick them anyway, regardless of the temp.

 

[acebars]

650Skull what is that graph for and where is that graph from? Doesn't seem right to me, the values for 10w40 seem too low, 10w40 is a common motorcycle oil weight.

People mentioning 15w40 Shell Rotella, this is not what I'm using, I've bought Shell Advance motorcycle mineral oil SX 4T 15w40 (which I don't think is the same thing). I understand a diesel oil at 15w40 is heavier than the equivalent weight in motorcycle oil.

20W-50 is the preferred oil for these engines. 15W-40 will work, but your top end will have that nasty tick-tick noise we all dread. When I had motorcycles back in the 1970's and 1980's, I always used 20W-50.

I use motorcycle specific oil, but that is an interesting factoid that 5twins mentioned, using non-motorcycle specific oil.

Perhaps I should relegate the 15w40 for winter use only then. Would love to find a bulk source of cheap 20w50 motorcycle oil in the UK, doesn't need to be diesel oil cheap but cheaper lets say.

 

[650Skull]

I go by that chart for the upper end, but good luck starting your xs650 at 25F with 20-50 in it Good luck turning the engine over even.

Don't need luck proof is in the fact. I'm sure you will have another unsubstantiated comment to say.........................Waiting...........

650Skull what is that graph for and where is that graph from? Doesn't seem right to me, the values for 10w40 seem too low, 10w40 is a common motorcycle oil weight.

People mentioning 15w40 Shell Rotella, this is not what I'm using, I've bought Shell Advance motorcycle mineral oil SX 4T 15w40 (which I don't think is the same thing). I understand a diesel oil at 15w40 is heavier than the equivalent weight in motorcycle oil.





Perhaps I should relegate the 15w40 for winter use only then. Would love to find a bulk source of cheap 20w50 motorcycle oil in the UK, doesn't need to be diesel oil cheap but cheaper lets say.

Bought my 83 Heritage while in NZ in the early 90's and all i used there was SAE 30.

No clutch slip and if i used the bike every day in winter it would start with the electric start but if i didn't ride for 2 or more days i would have to kick start it the first time.
I would ride when there was frost on the ground and divided my time mainly between Taranaki and Palmerston north and with the wind chill factor it could drop below 0 c

Always let the bike warm up, (idle wile putting on my jacket, helmet and gloves), before riding and still nursed it for a 1/2 mile at least

 

[pamcopete]

I have the official owners manual for my '81 H and it says to use SAE 20W40. There is also a placard on the left side air filter cover that says the same thing. This was about the time that the EPA started to take an interest in motorcycles so I think that the 20W40 has something to do with EPA compliance. Less friction means better gas mileage which means less pollution for a given engine speed, maybe. The EPA is not concerned with engine life.

All my other reading says use 20W50 and that is what I continue to use in my '81 H. One thing that convinced me was the pressure I see on my oil pressure gauge. The oil system is a nominal 15 psi system, but after the engine warms up, that pressure is more like 3 to 5 PSI at 3,000 RPM and drops to an indicated zero pressure at idle with 20W50 oil. That low pressure reading is basically the same winter or summer, so the notion that you should use a lower viscosity in the winter really only addresses starting the engine, not running.

The XS650 uses ball bearing in the crank and rollers in the connecting rod big end bearings so there is very little resistance to oil flow especially when it is up to operating temperature. That is why the pressure is so low.

My Honda CB750 uses Babbitt bearings in the crank and connecting rod big ends, just like a car engine. It has a pressure relief valve at the pump to produce a regulated 65 PSI for the oil system. The recommended viscosity for that engine is 20W40 which is high for a Babbitt bearing engine, but it tells me that you should use a higher viscosity in a air cooled motorcycle engine than you would in a water cooled car engine, so more evidence that 20W50 is appropriate for the XS650.

I also used to use 20W50 Pennzoil car oil because they maintained the zinc levels in those oils after they reduced it in the lessor weights for EPA compliance. However, they have within the past several years also reduced zinc in the heavier weights as well, so I no longer use car oil and instead use Valvoline motorcycle oil mainly because it is available at my nearby Advance Auto and is often on sale.

Some "Mineral Oils" are non detergent. A non detergent oil does not keep the carbon waste particles in suspension so the particles are deposited throughout the nooks and crannies of the engine and the valves. Try washing your undies with soap instead of detergent and you will see the difference.

 

[xjwmx]

Oh, they'll turn over. I usually take mine out at least once over the winter (if the roads are clear). Granted, the electric leg struggles, but a couple healthy kicks usually do the trick.

Maybe you overestimated the temperature. The reason I change in the winter is because a couple of times with the Pennz it might as well have been full of glue. With the Shell I've regularly started it in the teens. I wouldn't want to have the Pennz lower than about the 40s personally.

 

[650Skull]

I'm not advocating using SAE30. I did use it 23 years ago and we didn't get EPA restrictions here in Aus and NZ like you guys in the States did.

 

[xjwmx]

they have within the past several years also reduced zinc in the heavier weights as well,

How much zinc is necessary and how much is present? Does something else take care of the missing zinc's job?

 

[acebars]

On another note, would using 20w50 diesel oil be alright? I know several people are using 15w40 diesel oil.

It's significantly cheaper than the equivalent motorcycle brands.