Hi Folks!
A very common question with respect to the CBR125/150 series of bikes is which oil to use? There's a plethora of oils available, all making claims of one sort or another. I'd like to take a moment to address this issue once and for all with real-world experience and post up my findings...they are very accurate...
I went through this last year as I was racing the bike
daily against larger bikes and I noticed, right away, that
fresh oil was a LOT faster then used oil. The engine ran better, it shifted better and I did a lot better against my competitors. This was a very noticeable difference especially when competing against similar performing bikes where you spend a lot of time side by side in the same lane.
It started out with the oil lasting a week before performance and shifting started to decline. As I did more neck & neck racing, in the heat of the summer, I found that at the end of the day I could tell that the oil was no longer fresh (one day on fresh oil). At that point I switched over to changing my oil on a
daily basis if I was racing...
I got tired of changing out perfectly clean oil that was clearly being destroyed for some unknown reason at $7 a liter. It was costing 70% of the cost of a full tank of fuel raising my daily expenditure from $13 for fuel to +$20 with oil. That's a HUGE increase in running costs (almost double)
I knew there was no way that the oil could even get close to Honda's oil change interval when I was changing it out due to degraded performance within a week, or, on a daily basis!So I spent a lot of time looking into exactly
why the oil was getting destroyed. My research took me to an
oil engineer with a PHD in petroleum chemistry. He's made a fortune creating oil blends for large oil companies....
When I explained the situation to him he laughed and picked it off immediately because, as it turns out, it's quite common.
The oil is being destroyed due to oil shear. The reason why our bikes are particularly susceptible to this issue is because the oil is shared between the engine, the transmission, and the clutch. Add in an engine that's routinely turning 11,500 RPM and it's a recipe for killing a conventional oil in short order...
...but, it's also compounded by the fact that
our bikes only hold one liter of oil. If you think about it, that's one liter of oil that's being pressed into pretty severe service! :wacko:
When the oil gets passed through the gears in the transmission it gets the living daylights squeezed out of it :blink: This shears the oil.
When oil shears the viscosity increases. So, a 10/30 ends up being closer to a 20/50 when it's fully sheared out - or thicker...
This is why the bike slows down and why the shifting becomes more difficult. The oil is sheared and is now effectively useless. The engine and transmission are struggling against an oil that is now too thick and, as you know, our bikes only have a little bit of power, so anything that decreases that power is readily apparent to a rider who is perceptive as to how his bike is running.
When racing the bike with dinosaur oil I can shear it out
in one day if it's in the heat of the summer. The results actually show up in dyno tests that I've been running (if the poor performance of the engine/transmission alone isn't enough to convince the average rider).
So what's the answer to a long & consistent oil life?The answer is to run a
genuine 100% synthetic oil. A
true synthetic oil is
shear-stable.
The oil that was recommended to me by the petroleum engineer was Amsoil motorcycle oil. This is because it is a real, genuine, 100% synthetic oil with the base stock provided by Mobil 1, manufactured according to their OLD standards which are much higher then the current Mobil 1 specs. <ahem>
At that point, Amsoil adds in their own additive package and sells the product. This means that it is effectively the famed Mobil 1 of old which was always the best oil in the world and not a cheaper incarnation like Mobil 1's later 'blends' :top:
When you change over to Amsoil (or any quality 100% synthetic) you will see several interesting things,
- The oil will no longer shear and your bike's performance will stabilize whether your oil is fresh or old.
- You can now run the oil right up to Honda's oil change interval if so desired
- Your transmission will shift better because it's not submersed in oil that is as thick as ketchup
- Your engine oil will typically run about 25 degrees cooler - a common side-effect of true synthetic oil
- Your engine will actually make more power because it's not fighting against sheared-out oil that has thickened to well beyond it's original spec.
I found that Amsoil 10/40 is great and I was even able to get my hands on 0/40 which is even better (preferred) - weather permitting. With either oil the problems are gone. If you can get a liter for $15 at crappy tire it's a bargain and if you have to pay $20 it's still the best thing you can do for a bike that only takes <ahem> one liter of oil. The cheapest I've got it for is $14 and as far as I know, that's the lowest trade price out there. :top:
If you choose to put an end to this oil issue that is inherent in all of the CBR125's there are four other things worth mentioning, one, do a HOT oil change and tilt the bike to get rid of all the garbage oil. This will mean you need an extra 300ml of oil though (meaning buy two liters of Amsoil).
Two, you will hear more 'noise' from your engine whether it be bearing noise, valvetrain or what have you. This is a common side-effect of running real synthetic. Three, I've found is that it takes a bit of time for the oil to 'break in', 3 days or so but you don't have to be gentle to it - you can beat the living crap out of it all day long right from the pour. Four, your engine will actually run about 25 degrees cooler....which is important on a bike that only uses one liter of oil and doesn't have an oil cooler....
If you're balking about the price, consider how much you spend on changing it out more often and also what you spend on mods to increase your bike's power. Oil is not as sexy as some of those purchases but when you can change it and leave it in there for a long period of time, without a performance penalty, it becomes a pretty cost-effective modification. I just re-built the top end of my engine (at 20K) and it was very nice in there - you could tell that a quality oil was being run for most of the engine's life.
But, just to boil this back to basics, viewed solely as a performance modification alone, running Amsoil is a pretty big bang for the buck. Pictured below is probably the best oil you can get provided you don't live in an area where the temperatures are extremely hot.