10W-40 or 20W-40/50?

[boze]

ok i think ive filled my bike with the wrong oil.....ive filled her with 10W40 and ive just read in the manual to use 20W40 or 20W50. whats the difference and will i knacker my engine if i dont change it?

Damo

[mav617]

Recommended oil for my SZR is 20/50 but I use 10/40 as it's easier and cheaper to get hold of. The numbers refer to the viscosity and in this country at our average temps 10/40 seems to be the best compromise so I doubt you'll knacker it. is the engine noticeably more noisy mechanically than before?

[boze]

it is a bit louder, it sounds more "burly" than it did before, dont know if this is the oil or the fact that i had a smooshed exhaust gasket that i changed at the same time i did the oil change....

Damo

[mav617]

It should be fine, might use a little more of this than the heavier oil so keep an eye on the levels. I use 10/40s with some of that Wynn engine treatment (like Slick 50) which coats all the moving parts - apparently reducing wear when cold. Add some of this (Halfords sell it) if you're still worried.

[bikeseamus]

The single most important thing is to use 4 stroke motorcycle oil... not car oil.  You use car oil in it kiss it goodbye. The oiuls are entirely different and car oil is cat piss compared to an oil that is rated JASO and MA on the back.
   Cars don't share tranny and engine oil, so they can sort of get away with running garbage oil, especially since they are all liquid cooled, but if you put that garbage in a bike that shares engine and tranny oil, be prepared for accellerated wear in every component in the engine.
  As for running thinner oil than the factory tells you to... Cool...if you live in Alaska and are driving it at 40 degrees F, otherwise get that thin film stuff out of there immediately, if you value longevity. I aint guessing or bullshitting here.

[Steve H]

10W-40 should be fine. A good compromise between Winter and Summer use. The only time Ive used 20/50 is when touring two-up in Europe, the ambient temperature tends to be higher than the UK, meaning higher running temperatures on an air cooled bike, this can kill 10w40 quite quickly.
As mentioned car oils tend to have different additives and formulations which arent always appropriate for a bike, similairly I wouldnt use bike oil in a car for the same reason. 

[guest27]

However....  If you are miles from home and have run low on oil and car oil is all that the lil garage in Oldermunchie has - then this is better than running low / dry.

To save me diging out the explanation - which I cannot remember correctly - except that the 10 gives a cold weather and start up viscosity and the 40 is the hot running - is this right - will some one post a concise explanation of the 10W/40, 20/50 etc.

Thanks

R

[GB500nz]

Everybody I know uses car oil. There's no difference but price. Oil companies make oil and sell it to specialist companies who put it up in special packages for high prices. Avoid synthetic or semi-synthetic oil unless your manual says otherwise because these will screw up your clutch. Change every 1000 miles or so, because heat causes the oil to break down over time, and combustion products build up. I tend to use 20/50 in the summer and 15/40 in the winter. According to tests, Pennzoil has the best resistance to degradation, but I don't know.

[boze]

o0o0o i just snatched this off the sr500 forum:

I believe oils are rated as follows:
a 20 weight oil is relatively runny when cold, and too runny when hot.
a 40 weight oil is thickish when cold but reaches the right consistency when hot.
Therefore, a 20W-40 oil has the characteristic viscosity of a straight 20 weight oil when cold, but resists thinning when hot, so behaves like a 40 weight oil when hot. i.e. it has the right viscosity over a fairly wide temperature range.
Therefore a 20W-50 oil should to some extent be better, i.e. it is going to be the right viscosity/consistency/runnyness over a wider range of temperatures.
I would always be careful about going too low on the first number. i.e. you now see some 5W-40 type oils.

Damo

[Steve H]

To save me diging out the explanation - which I cannot remember correctly - except that the 10 gives a cold weather and start up viscosity and the 40 is the hot running - is this right - will some one post a concise explanation of the 10W/40, 20/50 etc.

My understanding is with a 10W40, when cold (it will be a defined temp) it has a viscosity of a straight 10W oil, when hot (again a defined temp) it will have the same viscosity as a straight 40W oil at the cold temperature. The idea is to reduce the chage in viscosity over the working temperature range of the engine.
If you ran a straight 10W oil, it would be fine for a cold engine, but really thin when hot, so of no use. If you ran a straight 40W it would be ok when hot but when cold would be so thick that the oil pump would struggle to pump it. Hence the variable viscosity. 
I would guess that this is why (in general) a 10W/40 will be cheaper than say a 5W/50 oil, as it has less modifiers to control the viscosity change.

[mav617]

OK,I'm confused now - are we saying that using Halfords 15/40 in my SZR is going to damage it? Where do you find specific 4-stroke motorcycle oil then?

[Steve H]

OK,I'm confused now - are we saying that using Halfords 15/40 in my SZR is going to damage it? Where do you find specific 4-stroke motorcycle oil then?

Its unlikely to damage it. I tend to buy branded oils (Castrol) rather Halford own brand, this is mainly for peace of mind rather than any specific problems Ive had.
My SZR ran very cold so a thinner (10W/40) oil might be of benefit, but I doubt you will see any difference.

[MrFluffy]

Id be nervous about using 10/40 instead of 20/50. I run a v8 rangie too, and the recomended oil for that dinosaur is 20/50, the one time that I used 10/40 after a change I was somewhat alarmed in the least to see the oil light flicking on at tickover (the v8's oiling system is a bit marginal at the best of times). The thinner grade leaks past the sloppy old bigends more therefore I could imagine some metal to metal going on during extreme useage so now I take the time to find the right grade of oil, Ive seen this story other places too so I doubt its just because my engines a bit shagged. Halfrauds sell 20/50 in their classic range, and B&Q sell some nasty budget stuff thats about 7 quid for 5L. I just use that in the ranger and change it more often. Yes theres probally more recycled oil in it, maybe some of the molecule chains are a little chopped up, but its been ok for the past 100k or so.
Id steer clear of synthetics in older engines, Ive seen some discussion how the extra chemicals in them cause age hardening on the rubber components on older bikes (camchain tensioner etc), plus the real advantages of synthetics (long service intervals) arent really applicable since I change my oil more frequently than regular intervals anyway. Cheap oil changed often, cant remember the last time I had a crank or internal bearing faliure...

As for the specialist motorcycle oil... hmmm... many many moons ago I used to work for a distributor of oil (cant reveal the name, but they were quite popular in the nw of england) and their motorcycle oil used to arrive from a refinery as 50 gallon drums marked "industrial use only" and be tapped off into small motorcycle sized bottles. The owner would change supplier depending on who was the cheapest on the day with no qualms or labeling change or anything...
When we were really bored and sick of working there and times were slow so we were on bottling, we used to put dead bees and flies in the bottles, hoping people would notice this big black squashy thing embalmed in when they opened the bottles and realised how pony it all was. I dont think the boss ever found out...

[guest18]

Ahh, you can always guarantee an argument when you start an oil discussion

I think I could dare to say that the majority of old riders on this forum would agree (more or less!) that as long as you change your oil at 1,000 to 1,500 miles then any oil of the appropriate grade will be fine as long as it is SAE/BS standard.
Oh and you should change the filter every second change at least.

If you are going to stretch your service interval (my MuZ has a 4,000 mile service interval ) then you need to consider higher spec oil (for that interval I use a well known brand of semi synthetic).

However as has already been said, any oil is better than none!

In answer to your question, I'd probably keep an eye on the level, swap it for the "correct" grade in around a thousand miles and as usual use it gently when it's cold. I certainly wouldn't lose any sleep over it

[002]

I use Lard for the Summer and Chip Fat for the Winter in my Enfield.
Never had a problem.
Except for the queue wanting Chips when I stop !

Jethro