Cars and bikes use the same oil, right? 10w-40 for a car will work? I don't know what API: SF or SG means.

I already filled it so I'm crossing my fingers....

 

There's fellas around that use automotive oils. Mobil 1 synthetic for example is a popular one. The only problem I see with not buying heavy duty oils is that they'll loose their lubricating properties rather quickly in a motorcycle engine, due to the shearing that occurs with the transmission. You should also be wary of "energy conserving" oils; they'll make your clutch slip.
As with the API classifications, those change every so often. So long as you're not using a rare obselete oil, you should be OK.

 

what he said, I use diesel motor oils. I just had Rotella-t full syn. in and not I have amsoil 15x-40 I like the amsiol Diesel/Marine better than the Rotella.

 

What you have to avoid is using oil that is designed for car engines, they contain all sorts of stuff (like detergents) that have an effect on your clutch (clutch slip) as the clutches on our bikes are oil bathed (share the oil with the motor.
Anyway:
Cut and paste from another site (http://www.agnr.umd.edu/users/Bioreng/fact181b.htm)


The American Petroleum Institute (API) Service Classifications are based on two engine service groups and a quality rating. The current API Service Classifications have been in use since 1972. For engines manufactured before 1972 the owner's or operator's manual will designate an oil according to an older API system. Consult an equipment dealer if there is a question about which classification of oil to use.

A typical API Service Classification found on a can or bottle is SG-CE. (See Figure 1.) The first letter of each of these pairs (S and C) denote the engine service group. API recognizes two engine service groups: the S series and the C series. The "S" stands for spark ignition - engines fueled by gasoline, alcohol, natural gas or propane. The "C" stands for compression ignition - oil fueled (diesel) engines.

The second letter of the pair denotes the quality rating. At this time a high quality rating for an oil is designated by the letter F or G. New quality ratings are assigned as better classes of oils are developed and tested. Generally, the new higher quality oils can be used where lower ratings were specified for older engines.

The engine service group and the quality rating are combined to give the API service classification such as SG or CE. The SG means it is for a spark ignition engine and has a quality rating of G. The CE means the oil is for a compression ignition engine and has a quality rating of E. A given oil may satisfy both engine service groups and have an API service classification of SG-CE, for example. Currently, SG (spark ignition, G quality rating) and CE (compression ignition, E quality rating) are the top engine oils in their respective categories.

The Society of Automotive Engineers (SAE) has established a scale which indicates oil thickness (viscosity). SAE numbers include, for example, 10W-30, 5W-40 and sometimes just a single number such as 5W, 10W, 20, 30, 40 or 50. The "W" next to a number means the oil thickness was measured at a very cold temperature, as low as -35 degrees F, when the oil is thickest. A number without a W suffix indicates the oil thickness was measured when the oil was hot (210 degrees F).

Two numbers separated by a hyphen indicate a multiviscosity oil. Multiviscosity oils are tested at both hot and cold temperatures and are recommended for all-season use. Multiviscosity oils are able to lubricate moving parts over a wide range of temperatures. These oils contain a viscosity index improver or polymers to change the viscosity of the oil as temperature changes. A multiviscosity oil such as a 10W-40 will function like an SAE 10W oil at cold temperatures and like an SAE 40 oil when the temperatures are warm or hot. Note that a multiviscosity oil can not be made by combining individual SAE oil viscosities together. Multiviscosity oils require the addition of polymers in order to gain the ability to function differently at different temperatures. Equipment operator's and service manuals specify which oil viscosity should be used under specific weather conditions.

 

Wow, thanks guys. I Appreciate all the knowledge.

 

http://motorcycleinfo.calsci.com/Consumables.html#Oil
lots of info here

 

Personally, I use NOTHING but Pro Honda HP4-S (in the red Bottle), non Molybednum oil, (Moly= silver bottle= clutch slippage) Even my non Honda riding buddies who also ride rockets use this oil, because even they realize that the Engineers at Honda do not F*ck around!
I would drain that s*it ASAP, and fill with it the HP4-S, it's a little pricy, sure, but how much is your baby's cardio health worth? Plus, by draining it and refilling it, you will be suprised how much extra crap will come out at the end of the drain, that stayed in your engine after the oil change you just did!

 

I drained it immediately, changed the filter, and filled with Honda 10W-40 GN-4(black bottle).
I got it at a bike shop for $21 for 4 quarts. Not bad.

 

I asked the same question a few months back when I was doing my first oil change. Rotella T was a popular choice so that is what I am currently running.