Originally Posted By: boraticus
I'm having a bit of trouble understanding the engine noise = wear assumption. You claim the valve train makes noise when cold and stops when warm. The sound of a valve opening and closing would most likely be from the spring force causing the valve to contact the valve seat. Oil has nothing to do with that. On a dohc engine, the cams usually contact buckets on shims sitting on the top of the valve stem. The meeting of the cam and bucket will make a bit of noise no matter what oil you are using. If you're hearing a tapping noise while the engine is cold, it's likely due to the cold clearance between the cam and bucket. As the engine heats up, the clearance is reduced as well as the cam/bucket contact noise. If the tapping noise goes away completely, that's not necessarily a good thing. On the contrary, it may very well be a bad thing. If the clearance between the cam and bucket isn't sufficient, the noise will virtually disappear because there is no lash. If there is no lash when the engine is hot, there's a good chance the valve(s) may not be closing completely. Here's a helpful tip: "Slappy valves are happy valves."
In my long history of owning small engines on many different machines, if there was a noise issue, it never had anything to do with the oil.
As far as missing a shift, I'd be a little embarrassed blaming it on the oil..... I've never had fresh oil cause shifting issues. Sure I've had oil near the end of it's useful service life that would let me know that the transmission wasn't liking it. However, missing shifts was usually due to not exerting enough force on the shift lever. Think about it. If I ride for a few hours and make a hundreds normal shifts and miss one or two, is it really the fault of the oil? If so, why wouldn't I be missing many more shifts? Old oil might reduce how slick a transmission shifts. However, with a minor adjustment of foot effort, shifts shouldn't be missed. New oil of any type has never caused me shifting issues.
Well now you know that a valve train can be noisy with one oil and be quiet with another oil.
You also know that some oils will stick to the machinery and some oils just slide off of it.
And you know that periods of inactivity will cause some oils to run off an engine completely, particularly when parked on their kickstand that leans the engine towards the cam chain's tunnel, leaving a DOHC design wanting for top end lubricant at start-up a week later.
All of this is due to the oil choice and not lash in the system. Change the oil and everything quiets down, even when cold and even after a week's inactivity.
The cam lobes act upon pivoted rocker arms and the rocker arms push on the shims and buckets. The rocker arm multiplies the lift on the cam. It can get quite noisy because there are more moving parts, but the lash is OK.
As far as shifts are concerned, I'll tolerate a missed shift on a country road but in high traffic it is dangerous. I have found one mix that virtually eliminates the problem. With the Rotella, the transmission would sometimes create a false neutral. Just too much friction from the oil.
This is the first motorcycle that has been fussy about oil. I go back to when HD's, Triumph, BSA, Norton, and Royal Enfield were all OHV: when 2-cycles "tried" to rule the world and then got legislated out of existence and Honda's Top Gun was a 305cc Superhawk.
