Hi there folks i am shortly going to do a service on my bike and usualy shell out for semi synthetic bike oil/ however after having an interesting conversation with a friend of mine at a motor factors i am thinking twice about paying the extra for bike oil. The subject of weither car oil was suitable for bikes came up and he being a biker told me that him and several of his friends one of which has a blade and another who races his bike at club level use granville platinum semi synthetic car oil which costs £7 per five litres. Now this guy recons that the specs on the oil match and exceed those recommended by japanese bike manufacturers but they just dont put the required number on the tin. Now im just wondering if oil manufacturers do this to inflate motorcycle oil prices i/e £25+ for what is essentialy the same slippy stuff. I Have heard about bike oil having friction modifiers in them to avoid clutch slip but then if you have an older bike its not recommended that you use fully synthetic oil as it can cause clutch slip. Id like to hear any views on this subject and maybe hear from anyone who uses car oil> i myself have worked in the car industry for many yrs and it is my opinion that modern car engines require just as good an oil as modern bikes so whats the score.!!! sorry for the length of my waffle guys.
Meny Moons ago
When I was a poor wee lad
Enough of that.
Once put regular castrol (car) GTX in my CBR1000.
It didn't like starting, it slowed engine pick up And went a bit bubbly at high rpm.
Never used it again. Never will (not unless you can really convince me )
I believe car oil is a no-no.
Not only because of the friction dooberry wot-sits but also coz of the make up of the oil itself.
Car oil has long chain molecules and this is fine coz it doesn't have to go through the gearbox in a car.
HOWEVER
On a bike the oil is used to lubricate the gearbox as well. All those nasty teeth will chop up the molecule and you'll get a much worse performing oil
I was told many years ago that as bike engins rev much higher than car engins, car oil would break down if used in a bike. Mind you, the red line on a vtr isnt that much higher than some sporty cars these days but I'd still be reluctant to try it though.
I agree with all the above but more and more car engines are becoming as high tech as bike engines in terms of rev limit etc. In some ways they are more so in the case of turbo engines. With regards to bens post i agree with what you say about the gearbox thingy but what about cars with gear driven variable 24valve blah blah stuf you see what im gettin at. I dont know but its an interesting point though init, why is bike oil so expensive?? im sooo tempted to stick it in my hornet and see what happens haha. thanks for your opinions guys.
I would say 100% no no. Cars have dry clutches and seperate gearbox oil. Bike oil is designed for higher rpm and has anti foam agents in it to stop the obvious, designed for wet clutches and why buy a good bike and skimp on the oil. It's like buying a super model and just feeding her chips, she ain't gonna look to good in a few years now is she.
No, no, only use synthetic MC oil.
I use the Motul synthetic oil and have never wanted to change it.
A friend of mine who works for C*****l says that high performance synthetic oils today is not necessary oil anymore but more additives with oil, uhm understand what I mean? Agree with all the arguments above.
Ok. VTR oil change ? about 4 litres (ish) every 4,000 miles so about 2 oil changes a year. Cost ? about £50. If car oil is 1/4 the price, you save about £37.50 a year, or about 9p a day in total. If you want to run the (albeit possibly minimal) risk of using car oil then go ahead. I will gladly pay the extra 9p a day for peace of mind !
As soon as I read about the dangers of drinking too much, I immediately gave up reading.
Although usually cars have separate oil for the gearbox some have not (the first that had not was the Mini Minor) but all cars have a dry clutch and reportedly this seems to be the reason to choose motorbike oil.
If you want to save a little money maybe you can use a mineral oil -- the VTR maintenance manual says it is ok.
OK, think of the money your saving by changing it yourself. I use Honda GN4 10W-40 oil for my Superhawk. You can get a case 12 quarts for $37.00 U.S. So thats under $10 each time you need to change you oil. I suprised that noone else mentioned the Honda oil that is listed in the shop manual. I would advise you to use a motorcycle oil at least. Since you seem to like castrol oil, they also make a motorcycle oil that you may want to check out.
Everyone is telling you correct. Car oil does not lub the gears & clutch enough. And if you ride like me, you don't want to do that.
if oil manufacturers do this to inflate motorcycle oil prices i/e £25+ for what is essentialy the same slippy stuff. I Have heard about bike oil having friction modifiers in them to avoid clutch slip but then if you have an older bike its not recommended that you use fully synthetic oil as it can cause clutch slip. Id like to hear any views on this subject and maybe hear from anyone who uses car oil> i myself have worked in the car industry for many yrs and it is my opinion that modern car engines require just as good an oil as modern bikes so whats the score.!!! sorry for the length of my waffle guys. 
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