My bike calls for 10W40. My question is it bad for my bike if I just put regular engine oil from my local auto parts store? I'm using the right grade but I'm wondering whether I should use a special formula. What do you recommend?

 

DON'T use motorcycle oil from your local auto parts store. Great article from sportrider.com (http://www.sportrider.com/tech/146_0308_oil/index.html) covers it in good detail, but the long and short of it is you want to use an oil that is rated for use in motorcycle engines.

 

Sorry...that should have said "DON'T use regular engine oil from your local auto parts store".

 

interesting enough, there are also articles and stories that say otherwise.
i say use whatever you like as long as it's non-energy conserving AND has no friction modifiers like molybedum or the like.

i switch back and forth from one type to another and at 40K, not a single problem.
i also know someone who runs vavoline 1040 and gets his oil checked every check up. he has like 20K and everything is fine...tests only shows that the oil did break down a bit faster...like at 2800 versus 3500 or so.

my friend has used mobile 1 on his F3 for 67K before he sold it...bike ran perfect.

 

I would use what is recommended for the bike, as you have to remember...our bikes have wet clutches, so I would feel much safer using the specified oil for the bike, as the oil is formulated for use as a motor oil, as well as a clutch "lubricant" if you will. But other members have more experience, as I am a beginner, but maybe this is why I am weary of using motor oil in my bike.

 

I like mobil 1 mx4t oil
makes shifting smoother

 

I'd strongly recommend that you use only oils designed specifically for motorcycles. Motorcycle oils, especially synthetic motorcycle oils, have been optimized for wet clutch applications and high speed sportbike engines.

When you consider the price of a top end overhaul or a clutch replacement, not to mention long term transmission health, using the proper oil is a good investment.