Ive heard alot of shit about this stuff, some people say it is good and some say it is bad.
People might think this is dumb but i clean my bike with it, as in, spray it onto a rad and wipe my frame with it, makes it shiny. I clean my chain with a toothbrush with it. and pritty much clean my bike with it.
But any way, just clearing up if it is good to use or not, and do u do if u get it on ur rotor?
wd40. is useful for nothing.. put it somewheres u cant find it, and never use it to clean ur bike again...this has been discussed many times on pb and doesn't need to be anymore, if u care for how ur bike rides don't use it, its a degrease, so its may be lubing ur chain, but its also taking off any grease thats on it.. it will do the same to anyother part that moves to.... just do not use it, use the tools made for the job...
As xlr8- said it will loosen up any grease on your bike, so use a proper oil/degreaser instead. Because if u use it on the fork seals for example it will loosen up any grease in the fork and i think even break down the oil in the fork. As u understand it will do the same thing to any other place on the bike. The same thing with 5-56.
WD40 is good in some situations... but not always... A degreaser is better but if you can't afford it you can use WD40... Just make sure you clean the area nicely before adding anymore grease or lube...
The problem people make with WD40 is thinking that its a lubricant but as long as you don't use it as a lubricant then its not that bad off a product.
WD is NOT a lubricant. Sure it makes ano nice and shiny (or paint for that matter) and it can clean chains decently, but is useful for nothing else. Its basically mineral oil. SIlicone oil works much better for making ano shiny, and it repels dirt and water, and chain lube is guess what, better for lubing chains.
its not a lube its a cheap efficient mineral based degreaser. its ok for shining frames and cleaning chains and cassets its also not bad for getting rustly bolts to move and thats about it.
"Arguably one of the two greatest inventions of the twentieth century (duct tape is the other),WD-40 was invented by Norm Larsen on his 40th attempt to develop a formula to prevent corrosion by displacing water. In addition to displacing water, WD-40 is a multipurpose problem solver that variously cleans, removes, dissolves, degreases, penetrates, and lightly lubricates various other items.The formula for WD-40 remains a closely guarded secret.As the saying goes, "If it is stuck and shouldn't be,WD-40 it. It if is unstuck and shouldn't be, duct tape it."The WD-40 Company did not pay me for this definition, but they should." teh internet
WD40 is good for cutting into rusted components.....Thats about it....Use the correct degreasers and lubricants for your bike....As far as a "polish" once again use the right stuff....I typically just use a bike or car wash on a rag then use a quality polish for the frame. If you do it frequently enough it also helps shead unwanted mud and dirt while you ride. As far as lube for the change look at what kind of riding you are doing and select the correct lube for that. If you ride on a dusty trail use a lube that is not so "wet" to prevent collecting dirt. If its very muddy perhaps an oil that clings and stay on the chain best....But most importantly degrease the chain first before applying new oil. Use proper degreasers, some strip too much away and leave the links dry in the roller section....
okay so i found one useful thing for wd40, i just ordered my seat post and i went to put it on my bike i greased the inside of the frame and the seat post, but i couldnt get it on, then i froze the seat post and still couldnt get it on, so i used wd40 and it poped right on, then i pulled the seat post out to where there was only like a few milimeters of the seat post in, wiped of the wd40 greased the seat post again (because i wipped it off when i put the wd40 on)and the seat post when in, i was very happy