Engine Oil
Engine oil is one of those subjects that seems as though it will be debated until the end of time. First, we'll look at some facts about motorcycles and engine oils, then we'll move on to opinions and advice.
The most significant difference between most motorcycles and modern cars is the use of a wet clutch system in motorcycles, where the clutch (and transmission) are bathed in the same oil that circulates throughout the engine crankcase. (One notable exception to this rule is the many BMW motorcycles with a dry-clutch setup.) Because of this, the clutch discs are susceptible to being too lubricated. If the oil is too slippery, the clutch can start to slip, and the only fix is usually to remove the clutch and replace the contaminated friction plates.
The EPA in the United States mandated the addition of further "friction reducers" to conventional motor oils over the past few years, primarily to enhance their "energy conserving" (read: higher gas mileage) properties. As a result, modern motor oils are becoming more and more slippery.
Because of anecdotal reports of clutch slippage with the new oils around the time of the introduction of the SH motor oil specification (the first specification with additional "energy conserving", or EC, additives), the Japanese Automotive Standards Organisation (JASO) published a motorcycle-only standard (called MA) for oils. M-class oils contain no additional "friction reducers" over those found in the SG standard and thus will not result in clutch slippage.
The Vintage Triumph Register, Texas VFR Garage, and Internet BMW Riders all have good articles about motorcycle engine oils that are recommended reading for the curious motorcyclist.
WARNING: OPINION AHEAD!
So what should you use in your bike? That depends on how paranoid you are and how much money you have. Perhaps it would be prudent to start with what you definitely SHOULDN'T use.
NEVER use any of the following in your motorcycle's crankcase:
- Cheap, generic gas station oil (bad idea in general)
- Oil additives (can cause clutch slippage, requiring a total clutch rebuild, which is somewhat expensive and very messy)
- Oil not meeting the minimum specification for your motorcycle (check your oil fill cap for a label, or consult a manual)
DO use a motor oil from a reputable manufacturer, such as Shell, Castrol, Mobil, Valvoline, etc. The quality control is better and the product is much better overall.
Use a motorcycle-specific oil if you're very worried about clutch slipping. If you aren't so worried about it, use a good quality major-brand oil without the "EC" label. There's an excellent discussion about it on KZrider (near the end of the thread).
As for synthetic vs. semi-synthetic vs. dino oil, experiences vary widely. If you can afford it, synthetics provide better protection (in theory), but will sometimes leak past seals in the engine. You'll probably want to try it for yourself and see how bad the leakage is. Keep in mind that all the rules above apply to synthetics and semi-synthetics as well.
You can get away with using an engine flush product like Gunk if you absolutely want to. The best way to do it is this:
- Drain the old oil and change the filter.
- Fill as recommended with cheap (but reputable) automotive oil in the proper weight.
- Use the engine flush product as recommended on the label.
- Drain out all the oil and change the filter again.
The short amount of time the car oil is in the system shouldn't cause clutch problems, and you won't be wasting good (and pricey) motorcycle oil flushing deposits and buildup out of the engine.
Fuel and Fuel Additives
The most important part of your bike's fuel system is the fuel itself. Buy a quality product from a reputable company (I currently prefer Shell fuels, as I find that I'm getting better mileage from them) and the likelihood that you'll suffer performance problems because of a bad batch of gas is greatly reduced. Larger gas stations also tend to have a higher rate of fuel turnover, which keeps moisture from accumulating in the fuel supply.
Many people will simply use premium fuel in motorcycles as a matter of practise, but in most instances, premium fuel is NOT required and can, in certain cases, actually cause problems down the road. High-octane fuel actually has inferior combustion properties as compared to "regular" fuel. When you think about it, this makes perfect sense: after all, the whole point of high-octane fuel is to prevent detonation (heard as a pinging or knocking sound), which is caused by a low ignition point and high burn rate of the fuel. Thus, if you retard the fuel's ability to burn, you raise its resistance to detonation. Using these premium fuels in an engine that doesn't generate high enough combustion chamber temperatures to approach the "knock point" will result in incomplete combustion and faster build-up of carbon deposits inside the combustion chamber.
The lesson learned is this: use the lowest octane fuel that prevents pinging in your engine. If you find that your engine requires premium to prevent pinging, you should consider running a couple tanks of gas through it that contain a combustion chamber/fuel system cleaner (such as Techron; more on that in a minute). A corrolary to this lesson is that fuel additives that increase the octane number of a fuel are likewise unnecessary and possibly harmful.
Many jurisdictions in northern climates mandate the use of oxygenated gasoline for at least part of the year. This usually takes the form of ethanol or methanol added to the fuel, although in some locations, methyl tert-butyl ether (MTBE) is used instead or in addition. Alcohols (and MTBE to a much lesser extent), when dissolved in gasoline, increase the solubility of water in the fuel. This will lead to rusting inside your tank, which will eventually be a problem. I highly recommend people living in these areas seal their tanks with a product such as POR-15 to prevent rusting. MAKE SURE the tank sealant you use is resistant to alcoholic fuels; there's not much point in sealing the tank if your sealant dissolves in the gasoline over the next two months.
A final point about gasoline: don't buy fuel at a station when a tanker has just delivered a fresh load of gas (or is in the process of delivering said load). The process stirs up all the solids and moisture in the tanks that normally settles to the bottom, and results in dirtier-than-normal fuel being delivered from the pump.
Now, for a brief discussion of fuel additives. A lot of people swear by Chevron's Techron. There's a good discussion of fuel additives on KZrider, with the consensus being (primarily) that Techron (if you can find it) is a great product, and Marvel Mystery Oil (aka MMO) is also excellent. Use one or the other regularly in your fuel tank, and your fuel system will stay cleaner than it might otherwise. Seafoam is also highly recommended, though it seems to have less of a following than MMO or Techron. The Texas VFR Garage also has some useful information about fuel additives that you might wish to read. No matter what you decide, it seems prudent to avoid mixing additives in a single tank of fuel. If you want to use more than one additive, rotate the usage from tank to tank.
When cleaning the fuel system of a bike that hasn't seen additives much (if ever) before, run the additive with the first few tanks of gasoline in the recommended dosage. After that, back off the additive to once every other or every third tank. In normal usage, it isn't necessary to run the additive in every single tank.