Changing From Castrol R to Mineral Oil

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I have a 1964 Royal Enfield 250 which ran with Castrol R for a couple of seasons in classic racing. I want to change back to a mineral oil, as I plan to use it as a road bike and Castrol R is not really suited to that kind of use; normally being drained and refilled at each race meeting.

Castrol simply advise flushing the engine a couple of times with a mineral oil, should remove any residues but I am concerned as I have read numerous recommendations that the engine needs to be stripped and thoroughly cleaned to remove all traces of sludge and varnish before this comes into contact with mineral oil.

I guess that, since the castor will not dissolve in the mineral oil, it will circulate as a gloop and hopefully exit via the filter or drain plug, provided the oil ways are clear. But I am concerned as to how it will behave in the plain and roller bearings.Does anybody have experience of changing from castor based to mineral oils, either flushing or stripping ? Any recommendations as to a good flushing oil for caster oil ?
 
Wow..I used Castrol bean oil many, many years ago. Yes it must be changed very often. When I converted over to mineral oil I did a couple of quick oil changes with Rotella (ran the bike like 20 miles and then dropped the oil two or three times)

This was a long time ago on a Ducati road racer. When I did strip the engine the internals were nice with the exception of some bean oil varnish here and there in some casting corners. Not a big deal. Over several oil changes the bean oil would of cleaned up.
 
Thanks for the info, DB_Cooper that sounds good; haven't come across Rotella, I think it's a Shell oil brand ?

So you just flushed few times with basic mineral oil, rather than use a specific flushing oil ?
 
Rotella is/was a HDEO..or over the road truck oil. I used Rotella 40w when racing with no ill effects and Rotella is probably similar to Shell Rimula over there. I doubt a "flushing oil" is really needed or wanted.

In the USA Rotella is not too expensive. As you will need to do several fill and dumps of the crankcase I think any off the shelf reputable HDEO would be fine..15w40 should be available and a good throw away oil.
 
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