Oil requirements for 50cc GY6

[gab]

While doing my large amounts of research as usual something seemed off, the required oil and the oil often found available on most sites does not correspond with what is said in manual. (Manual says SAE 5W-30)

I have looked for my answer on here and many conflicting results arose, nothing was right until i looked at the manual itself. Many questions have arisen;

Is 5W30 Oil the better viscosity?

Are people deliberately not looking at manual spec?

Is any other grade better than what is said in that manual?

What are your thoughts on the ratings for the engine? What is your experience in this matter?

Should I put in what the manual says?*

*I know for a fact that you should basically always do what the manual says, but on the forum tech info, I saw Brent use 15W30 in the images. Thus my current questioning.

[wiscootsin]

it's pretty common to use rotella on cheap gy6 engines. I don't think anyone has any specific science around it, but the china engines aren't put together the greatest. the oil used likely doesn't become a huge factor for what they're doing.

There is also the matter of each chinese manufacturer having it's own broken english manual, and likely having some different SAE oils listed, even though using the same engine.

frequent oil changes likely makes a bigger difference than oil viscosity thrown in these things. Check dipstick while scooter is on flat surface. If overfilled, use an old pumper from a shampoo bottle to take some out.

[GrumpyUnk]

My observation, possibly self-serving as I agree, is that many use oils designed for diesel engine use. Rotella, Delvac, RPM Delo, and of course Walmart SuperTech brand in 15W40 should more than meet the requirements of the GY6/139QMB engines. Likely any diesel designed oil should be more than adequate if changed regularly. I think the engine was designed to live through zero changes in multi-year use... They get abused and keep on running overseas. The cylinders are regularly bored .5mm over, and fitted with piston/rings to fit. Not the big step sold in BBKs. This is to keep them on the road when they are worn out. Discarded OEM factory 49cc cylinders in the USA have LOTS of room to be bored oversize and fitted with BBK rings/pistons. I have a stack in the basement, but don't have a boring machine...
I would suggest removing both drain plug and filter screen plug when changing the oil. One on the bottom, one on the side of the crankcase. You get a more complete drain, I think.
When filling the crankcase, take your time, and be sure to check the level when both tires are on the ground.
tom