The Honda Owners Club

Can anyone help, I have just rebuilt the wife’s Honda 1982 CB650 Nighthawk SOHC and not too sure what oil to put in the engine. I have heard that some of the semi-synthetic oils can cause smoking, any help would be appreciated.

loz400 wrote: I have heard that some of the semi-synthetic oils can cause smoking

Not heard that one before. Where have you heard that, and any ideas as to what brand? I should think you would be OK with just about any motorcycle-specific brand of semi-synthetic (10W40) oil. I've used Silkolene Super 4 semi-synthetic for years. There are plenty of other brands available though.

I have also heard of this on older motors. The reasoning is that when running in an engine, normal mineral oils allow the rings to bed in whereas the synthetic type oils "glaze" the bores very quickly. (By doing what they do best, making the mating surfaces very slippery.) In effect, the rings and bores don't mate together properly and this causes the gases to flow past the rings and oil to enter into the pot. Result is a smoking engine.

I would suggest use thinnest mineral oil allowed for the initial run in, then change to a semi after first oil change.

Hope this helps

I used a normal 10w40 mineral oil in my CB550 and changed it once a year.

Ran fine on it and didn't use much between oil changes.