question about motor oil for the xj750

well i put motorcycle oil 20w 50 and the throttle response lags but when i put car oil which i've been putting for many months, at high rpm, the throttle response is strong and not laggy at all. I put 10w-40 castrol regular car oil for about 7 months now.

 

You only want to use oil made for wet clutch motorcycles. Car oil has friction modifiers that make the clutch slip. Since you've run car oil so long you may end up putting in new clutch disc's.

 

I heard others putting castrol 10w-30 car oil in their xj750 without a problem. I was wondering if i'm wrong and misread this somewhere on this forum. i also heard that rotella shell is good for this bike too.

 

i too put castrol GTX 20-50 into my bike but found it took ages to warm up and shifting was a bit hard,changed to motorbike oil 15-40 and shifting became so much easier,you could feel the difference instantly, thats with my bike anyway.

 

You heard right, EXCEPT -
It seems they changed the formula last year (I think?)
Now you need Castrol 4T, but I hear it shears "out of grade" real quick.

I like the Rotella (non-syn)

 

thanks for clearing that up. I'll try using rotella on my next oil change

 

i use oil for diesel trucks

 

What you need to stay away from, in the US anyway, are oils with an "Energy Conserving" designation. These are the oils with the friction modifiers that cause problems on wet clutch applications. IIRC, the designaion isinside a triangle shaped graphic and they are fairly obvious.

I use Castrol 20W50 4T (a designated motorcycle oil) because it contains additives removed from automobile oils. The additives are zinc and phosphorus. Oil mfg's inthe US were required to remove these two elements in order to meet EPA pollution standards.

I use 20W50 exclusively as the bike I ride everyday in the winter (non-snow, non-ice) is a water pumper. The summers around here are warm enough that theMaxim does just fine with this weight oil.

Loren

 

Car oil made my clutches slip so I just went with Mobil Motorcycle oil, works great and doesn't cost much, Would rather play it safe than replace clutches again. :wink:

 

I wish there's a way for me to decribe fully what I experience its just I'm not a technician or an engineer, when I put in motorcycle oil in my engine, the torque is signifcantly lost, when I put in castrol gtx 10`40, I have torque at mids. Is there a reason why that's the case for this bike?

I'm talking really significant. For instance, if a car and I are going 60 and I need to speed up and pass it, the torque really gives me a significant boost to pass the car without a hitch. Its not a sportsbike but its its runing faster than a 883 sportster. I have a xj750 seca.

 

You sure you weren't experiencing clutch slippage and not a "loss of torque?"

The difference between say, Castrol GTX 10W40 and GTX 20W50 shouldn't affect how the bike runs.

 

The 20-50 is motorcycle oil and the 10-40 is regular car oil, to clear up any misunderstnadings, my cike runs better with the car oil, it may sound louder but its faster and torque pulls better.

 

No "loss of torque" like I've said prevously. Started, I'm experiencing better torque.

 

I have to admit this is the first time i ever herd of being able to tell the difference between 15-40 and 20-50 by the seat of the pants. It might take about 1/4 hp and that is from the extra drag on the oil pump or so difference at best. Now i can believe it might be quieter and possibly shift better. Maybe you think it runs better because its quieter

 

To clear up the misunderstandings, its "motorcycle oil" vs "regular car oil". it was stated in previous replys

 

We know that regular, modern, car oil will quickly kill a motorcycle clutch. If you had car oil in, and changed to motorcycle oil, you may be, and likely are, experiencing clutch slip.

Did you put the car oil back in? Did that eliminate your problem when and if you did?

 

Sorry guys if there's any misunderstandings, I've never siad I have clutch slip, others have said they do but I've said I have higher torque. Does anyone else have the same situation?

 

That's because there are many very experienced and knowledgable mechanics on this site, and that's the only thing that makes sense.

If you had car oil in, and then changed to motorcycle oil, I can understand how you would appear to have more torque with the car oil in. It's cause your clutch is slipping when the engine is putting out peak torque, and it's not getting to your rear wheel. It wouldn't seem like the clutch is slipping if it's only when you are already in gear, mind you...it would feel like there is no power.

If you had car oil in, put motorcycle oil in, then put car oil back in and it went away, then I don't know what to tell you.

If you had motorcycle oil in, and you now have car oil in (that's not what you seem to be saying, I'm just covering all the bases) and now you seem to have more torque, I'd say it's all in your head.

 

Sorry for any misunderstandings but I've nver stated once that I had put car oil and it made my clutch slip.

If it was all "in my head" than that's the worst explanation why my bike is giving out more torque with car oil than motorcycle oil. I've stated many times on this post that I'm not a technician or an engineer but I know my bike is pulling easily with torque with car oil. And plus I'm kind of tired of people not reading previous posts and than posting their answers that might seem related and sure you have more experience with this bike because youkve owned it for years, doesn't mean my experience should mean and lesser. This bike has been a daiy commutung bike for 9 months for me. Well I would say this post is now a means of proving instead of a means of how or why car oil brings out more torque.

 

Lets try again...I'm really just trying to figure out what your experience is...I think it is one of the situations below, but I can't figure it out from your posts...

A) You had car oil in, then you put motorcycle oil in and experienced less power. The end.
B) You had car oil in, then you put motorcycle oil in and experienced less power, you put car oil back in and regained the lost power. The end.
C) You had motorcycle oil in, you put car oil in and gained power.
D) Some other situation.

I know you don't feel your clutch slipping...I get that...but if it were slipping, you might not know it. It would FEEL like you were losing power when you hit the throttle....that's all I'm saying.

There should be no reason an engine's power output at the flywheel would be affected significantly by different oils of similar viscosity and age. If this is your experience, it would be most mechanics belief that the increased power is a result of something other than the oil, even though it may have happened at the same time as the oil change.

 

Its not that straight forward.
Motorcycle vs Car oil

AND

10w40 vs 20w50

You have two dynamics that have changed

 

When I worked on cars the rule of thumb was if you had more torque with lighter weight oil, it was because of semi-blocked passages not allowing the thicker oil to pass thru. Hope that's not your problem. Usually thicker oil seals the cylinder wall to ring gap better adding better compression and the feeling of more torque, which isn't very good either. :roll: