One of the best things you can do for the longevity of your scooter’s engine is change the engine oil.
We (and most manufacturers) recommend changing the engine oil when you first get your scooter prior to even starting it (a good scooter dealer should do this for you as part of the prep work prior to delivery). You will then want to change the oil again after a short break-in period (300KM). From that point forward, you should change your oil at every 1,000KM on your odometer or more frequently if you are riding in more severe conditions.
With the importance of oil changes in your scooter, we often get the question from scooter owners as to what type of engine oil they should use in their 4-stroke GY6 scooter motor. While the topic of oil gets hotly debated (as to which brands, synthetic or non-synthetic, what weight, etc.) is best for your engine, we will try to shed some light on the subject as it pertains to the 50cc and 150cc GY6 4-stroke scooter engines. Please note, this discussion only applies to the 50cc and 150cc GY6 4-stroke scooters (denoted by a 139QMB or 157QMJ engine number) found on many of the modern Chinese and Taiwanese scooters. It does not apply to other scooter engines (2-strokes, older model scooters, etc) – for those we recommend consulting your owner’s manual.
Viscosity is the “flow rate” of a liquid; the greater the number, the greater resistance of the liquid to “flow.” As an example, water has a much lower viscosity than honey (neither of which we recommend for protecting your engine). Multi-weight engine oil is denoted by two numbers (example 10w-40). The first number is the viscosity of the oil at cold temperature; the second number is the viscosity of the oil at engine operating temperature. Thus, 10w-30 has a lower viscosity at engine operating temperature than a 10w-40 weight oil as denoted by the 30 vs 40.
The trick to finding the correct engine oil for your engine is getting one that has the correct viscosity at cold temperature so that it can flow thru your oil pump and passageways to your valves, camshafts, etc. at cold start-up; while also maintaining a high enough viscosity at engine operating temperature to properly lubricate all the metal to metal components in your engine. If you go too low for your engines recommended viscosity, you lose valuable lubrication. If you go too high for your engines recommended viscosity, the oil does not flow correctly thru the pumps and passageways to get to where it needs to be to lubricate.
As such, most engine manufactures denote a specific oil weight or viscosity for their engine design. With the 50cc and 150cc GY6 engines, most manufactures recommend a 10w-40 for colder winter weather, and 15w-40 for hotter summer riding. This makes sense, (recall the first number denotes viscosity at cold temperature), so a lower viscosity (10w-40) in the cold months of winter help the oil flow more easily to vital components at cold start-up, while moving to a higher 15w-40 helps lubricate a bit more at cold start-up in the hotter summer months.
Synthetic vs. Conventional Engine Oil:
You will find that the subject of using synthetic vs conventional oil in your scooter is hotly debated on both sides. As a general rule, we recommend using conventional motor oil during your first 1,000KM break-in period. Synthetic engine oils just don’t tend to break-in the engine as well as conventional oils due to the differences in formulation and additives.
After the first 1,000KM break-in you can switch to synthetic oil in the correct viscosity range for your engine (10w-40 or 15w-40). Reportedly, synthetic oils tend to lubricate better at higher temperatures, and break down less quickly in the high-heat air cooled scooter engines. However, a word of caution on synthetic oil… as with many small engines, we have heard reports of some engines leaking synthetic oil out of the engine crank seals. While it happens in a small number of cases, we certainly recommend that if you do decide to switch to a synthetic oil, check your engine for leaks and check the oil level on your dipstick very frequently for the first few oil changes. By doing this, you can insure that if you are one of the small number of scooters that leaks with synthetic oil, you can catch things before it causes damage to your engine.
With the price difference between synthetic and conventional oil, we find that many scooter owners tend to stick with conventional oil. Many owners opt to change oil more frequently with lower cost conventional oil (say every 800KM) vs. using higher cost synthetic engine oil and changing oil every 1,000KM. We don’t have a strong option in favor of either approach, but very strongly believe that routine oil changes at or below manufacturer’s recommended intervals with the correct viscosity oil is really the key to a long lasting engine. Use of synthetic vs. conventional is really up to personal preference. Either type of oil with regular changes will give your engine a good and happy life.
Motorcycle Specific Oils:
Most modern motorcycles have a “wet” clutch, meaning that the friction plates in the clutch are also lubricated by the engine oil. Motorcycle specific oils are made to provide the right amount of lubrication to the engine while at the same time having additives that allow for the clutch to operate properly. On motorcycles with wet clutches, use of regular automotive engine oil can cause the clutch to slip.
The 4-stroke GY6 engine used in most modern scooters does not have a wet clutch like a modern motorcycle (rather they use a belt driven CVT transmission which is “dry” and not in contact with engine oil). As such, there is no need to use motorcycle specific oil for your GY6 scooter.
What Oil to Use:
In short, for your 50cc or 150cc GY6 engine:
- Change your engine oil at or before the manufacturer’s recommended intervals1
- 10w-40 weight oil for the winter months
- 15w-40 weight oil for the summer months
- Use quality oil (any of the major name brand oils are fine)
- Use conventional oil during the first 1,000KM break-in period
- Option to switch to synthetic after 1,000KM, but is a matter of personal preference (if you do switch to synthetic – check frequently for any leaks to make sure you are not one of the small number of engines that leaks synthetic oil)
- No need to use a more expensive motorcycle specific oil
Happy and safe riding!
Metro Scooters, LLC