Expert: Bill Silver - 6/28/2009

Question
Hey Bill, So I've recently bought a 1970 CT90 and I'm looking to change the oil. The fella I bought it from suggested Non detergent oil to prevent any build up that's accumulated over time to break off and gum things up. Now, keep in mind that the engine has all of 80 miles on it (I know, it's amazing, but the odometer really looks original and not tampered with). The manual I found online here: http://is.gd/1gqZR expressly suggests using Detergent oil in it, so what is your opinion? Also would you say 10W30 in the forks or a specific fork oil? The manual says 10W30 on that one too. Thanks in advance.

Answer
Jacob, ND oils are getting kind of scarce now. With next to no miles on it, I would use a good quality 10-30 wt regular motorcycle oil for the next 500 miles.

Go through it and adjust valves, set timing, clean carb, etc...

You can use a thicker fork oil in the forks, or 10-30/10-40 in there. It really doesn't make much difference in these forks, unless you are driving it in sub-zero temperatures!

Bill Silver