lens cleaning

Generally, I use some liquid eyeglass cleaner on my scope lens.  I also have a Leupold lens cleaner/brush.  I usually try to blow of any visible dust/sand immediately.  Now I have flip up Butler lens covers on all my scopes, so the lens stay pretty clean.

But a friend gave me a nice old scope that he said had clouded over due to age.  He figured I had lots of old guns and it might be a period match.  It has an Orange cast to it.  This guy doesn't believe in scope caps, says they slow him down on fast shots (I'll not address that).  But I have noticed he cleans his guns with oil and other cleaners around and the lenses open. 

After a few months with this old scope on the bench I started thinking that this coating might be some cleaning fluid build up????  I also know this guy uses WD-40 a lot to clean and lubricate his guns (I'll not go there either).  So I got to thinking.  WD-40 tends to build up a coating on metal, slightly orange in color.  Might this be just a lens coating.  So I cleaned the lenses with some optic cleaner (Pearle vision).  No change.  So I got thinking again over a few weeks.  How about the wd-40 doesn't respond to water based cleaners??????  Maybe I should try something else.

I had thought of asking on this board, but got determined thinking of all the times I'd seen this guy 'spray' his guns with WD-40 when they got wet. So I took some cotton balls and soaked them in rubbing alcohol.  A few cotton balls on each lens gentle rubbing.....perfectly clean lens.  I was concerned with damage to an old lens optical coating.  but everything worked out fine.  And I have a nice old 4x scope gin clear.

BEAR