Multiviscosity oil changes it's viscosity (ability to flow) depending on temperature.
15w-40 basically means at about 0C (freezing) it will flow like a 15 weight oil and at 100C (boiling) it will flow like a 40 weight. W means "winter".
Thin oils do not protect a hot engine under high load in the long term because they lack the film strength.
Even if an engine is designed to use a specific weight of oil, it is acceptable to use a thinner or thicker weight oil if the temperatures accommodate it. If an engine is specified to use 10w-30, it's perfectly acceptable to use 5w-30 or even 0w-20 if it's well below freezing. At temperatures of 40 below zero, a thinner oil is needed for cold starts and some engines may never get to full operating temperature.
I recommend 15w-40 for all-around use on our 4-strokes. 10w-30 if you find yourself riding in freezing temperatures or colder. My reasons:
1) Our engines were designed for stationary use at near constant RPM. A stationary engine is not necessarily exposed to the wide range of temperatures or RPMs at intervals that ours are. 15w-40 covers just about any temperature we ride at, from freezing to very hot days.
2) 15w-40 is almost always designed for industrial heavy-duty use. This is the weight of oil that big diesel trucks and most industrial engines exposed to wide temperatures use. It usually has additives that enhance it's ability to protect engines under hard load. Our little industrial/commercial engines deserve the same level of protection.
3) Our engines aren't always level and they don't have an oil pump. They don't hold a lot of oil. Our engines are often on bicycles and that means we lean in corners. Thicker oil has more film strength, which means it "sticks" to engine parts a little better than thinner oil. During that time you're leaning in a corner, your engine theoretically has more oil where it needs it. Racing cars use straight 50 or 60 weight oil for good reason.
As for changing the oil on your Huasheng, there's several ways to do it.
1) You can remove the engine. This is what i did for the first year, since it was quick and easier for me to access it (SBP shift kit).
2) You can get a
Drainzit HON1010 remote hose. This screws into the engine where your oil drainplug is and makes oil changes much easier. I have one and think it's a great little part. Draining the oil makes no mess unless you point the hose in the wrong place.
3) You can make your own drain hose. Take a 1-1.25" long 10MM bolt, cut the head off, drill a hole through the middle. Screw that into your engine and attach a hose with a hoseclamp, put a petcock on the end. Home-made remote hose.
4) Scotto's method. Get a bulb-end turkey baster and use it suck the oil out of the fill hole. You can also use it to put a precise amount of oil in your engine. There are other oil change aids that use the same principle.
thank you so much. So royal purple 15w 40 is the best to use. I can't thank you enough. Maybe you should make that a sticky in the 4 stroke section.
