Solvent To Remove Caster Oil

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Need to clean an engine which has been filled with Castrol R for several years; anybody done similar ?

What is a good solvent for caster oil which will not attack rubber seals ?
 
Caster, Castor, or Castrol??

When I saw your title, I thought you meant castor..............you know that old school stuff your grandma made you take. (LOL).
 
I would just fill with fresh oil and possibly change early.

just getting the fresh oil hot should do a gentle cleaning of the old oil.

or is it all sludged up?
 
Last edited:
Originally Posted By: tridentt150v
Someone has suggested methanol or acetone, to flush without stripping the engine..... any advice ?


I would only use a solvent if you do a stationary flush. Meaning.....Fill the engine, let it set, and drain again, without turning it over.

Personally, I would drain the Castor oil hot, refill with the mineral oil of your choice, and repeat. A short OCI after using the mineral for a flush should be sufficient. The castor oil may not mix with the mineral properly, but it should drain just fine.
 
Originally Posted By: 4wheeldog
Originally Posted By: tridentt150v
Someone has suggested methanol or acetone, to flush without stripping the engine..... any advice ?


I would only use a solvent if you do a stationary flush. Meaning.....Fill the engine, let it set, and drain again, without turning it over.

Personally, I would drain the Castor oil hot, refill with the mineral oil of your choice, and repeat. A short OCI after using the mineral for a flush should be sufficient. The castor oil may not mix with the mineral properly, but it should drain just fine.


I thought caster was a typo and it was castrol?
 
I think your concern is that the Castrol R may have oxidized to a sludge or even solid over time in spots? Known to do that. I have no personal experience w/that, but have read of it on the SOHC4.net site.

I've used, w/great success, ATF as a combination solvent/lubricant in engines with sticking rings, gunk, etc. I'd be tempted to use a cheap motor oil in the right grade for the engine and ATF in 50/50 mix, run it at idle and low throttle w/o load for 15 minutes. Drain, repeat as indicated.

This is a very sold-school engine cleaning technique with many decades of proven results. Were it my bike (I'm presuming this is a bike of course), I'd have no qualms about doing this. 'Cept on a Harley with their very different oiling needs. I'd still do it there, but a different ratio.
 
You can fill the sump with solvent (kerosene, mineral spirits) and let it soak then drain but my concern would be loosening the gunk up and then having it get pumped through the system and possibly plugging something.
 
Originally Posted By: Rand
I thought caster was a typo and it was castrol?

Castrol R is made from castor beans. I believe that is how Castrol got its name.
 
I use a heat gun in a sized engine from oxidized castor oil, it always got free again. No need to solvents. Just run it more often and it won't freeze in again.
 
Castor oil was usually used with methanol, using rich mixtures a lot of methanol would get in the sump and they will mix. Castor oil won't mix so well with petrol. I'd flush it out withm meths.
 
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