Engine oil

[nick crisp]

So, if you're happy to buy the cheapest 10W-40 that you can find in Asda for your bike, and are convinced that motorcycle oil is just car oil with the word "motorcycle" on the packaging you might wonder why oil companies provide oil of unnecessarily high quality for under-stressed engines.

Simon.Pieman/VNA: I have used car oil (and not the cheapest) in bikes and regretted it… not that the engine actually broke as a result, but power gradually dropped off as the cam lobes suffered excessive wear.

Most of what is being said here is opinion and here say, not fact.

Pretty much all we have to go on are specs. 

I think we are just going round in circles. 

OK, here's a question, does anything in the spec on the can tell you whether there are friction modifiers or not?  I don't think there is.  There may be clues like 'optimised for fuel economy' in which case you avoid like the plague.

Lets face it oil companies, as far as I can see, manufacture an oil to meet a spec.  Then they can re-brand, if they wish to suit.  They can stick a picture of a car on one tin, a bike on another, a truck on another etc.  The stuff in the car tin may or may not have fiction modifiers in it.  But a picture of a high performance bike is always a great opportunity to shove the price up. 

Also the quality of car oil and the demands on the stuff have increased considerably in the last decade.  Have a look at the specs, say for example, of some of the latest small capacity turbo charged car engines.  Note the impressive BHP and torque figures, plus it's got a turbo to contend with and a 20,000 mile service interval.

You could spend quite a bit of time figuring out oil specs, maybe contacting oil companies for the finer details (they may or may not want to be helpful) and will probably end up buying a far better oil for a much better price for your bike, and I bet it won't have a picture of a motorcycle on the tin.

Oh don't forget truck oil.  They probably have the highest specs of all road going engines, and could be just the ticket for the bike.  You'd have to buy a big drum though.

But seriously unless you really know your oil, most of what is being written here (maybe my post too?) is just hot air.

I just buy a semi synth with a picture of a bike on the front.  Expensive, and last time I looked up the spec years ago, pretty basic too.  But I haven't yet bothered to work out how to get something better for less for my bike.  Probably because the time ain't worth the tenner a year I'd save.

Which is all why I read what I can on such subjects. Where sources disagree, ok the jury's out, you may never know. But if you get a good consensus of opinion across as many sources as you can find, then that's probably your best guide. You're absolutely right, opinions from the layman (ie most of us) aren't much use. But there is a wealth of information out there from professional sources, it'd be churlish to ignore it. I've worked in a lot of bike shops down the last 15 years or so, ok, not as a mechanic/technician, but I listen, and yes I've heard conflicting opinions about many things, but gradually you narrow it down to the things everyone agrees on. I like to think that's what we're trying to do here on this thread and on others like it. So I pay more attention to the guys who say, "this is what I did, and this was the result", rather than just "this is what I think". And if you're still not convinced, well you store it away until further information comes in and then assess it again. In this particular case, we all use oil, so it makes sense to try to find out a few facts about the stuff.