Castor oil

I recently bought a bike (Not Norton) that has been using a castor based oil ever since the motor was built. I believe that I can't change to a "normal" oil without stripping and cleaning the motor, which as it runs so well, I am reluctant to do.
Anyway, this bike has no oil filter (save the oil tank and sump) so :-
Is it ok to fit a canister type filter or not.
thanks
sam

I have never heard of a reason NOT to run a filter; I'd like to hear the answer to this question, too...

My experience with castor oil (specifically Castrol "R") has been limited to oil/gas mix 2-strokes. It doesn't dissolve in gas like petroleum based lubricants, so it can be a problem keeping it mixed. We switched back & forth on the prototype AJS Stormer.

As long as your "castor-based" lubricant is one designed for use in engines, not a kitchen or medicinal version, I'd be tempted to stick with it. If it's outrageously expensive and you want to switch to a petroleum oil, running a flushing oil through for some time with the engine idling should be enough to make the change-over. Tear-down shouldn't be necessary.

Any 4-stroke engine that has done considerable mileage with bean oil in the sump probably needs a top-end tear down and cleaning in any case. Although bean oil is very slick and a good lubricant. heat tends to make it form varnish on the pistons, especially in the ring and ring land areas.

Racers like bean oil and get away with using it exclusively because their motors are constantly torn down, cleaned and inspected to keep them in top running order. It always cracked me up seeing all the oil sponsor stickers on big-time flat track bikes when all you could smell was beans when they roared by on the front straight of a mile or half-mile.

trident sam said:

I recently bought a bike (Not Norton) that has been using a castor based oil ever since the motor was built. I believe that I can't change to a "normal" oil without stripping and cleaning the motor, which as it runs so well, I am reluctant to do.
Anyway, this bike has no oil filter (save the oil tank and sump) so :-
Is it ok to fit a canister type filter or not.
thanks
sam

Click to expand...

Hi Sam,

Yes you can switch from R to other oils provided you use a proprietary engine flush and change again after a few hundred miles a couple of times. I have done it before without issue.

I can not think of any reason not to use a canister filter, provided it is on the return where it cannot impede feed flow. If mounted after the take off to the head (assuming that's how the head is fed) the extra back pressure can lead to increased oil flow to the head, usually a good thing. If you want to be really flash you could plumb the filter in between the pump and the crank (via external plumbing) which is what Nourish did on his engines, and running R too. But IMHO, a filter on the return is as good as anywhere.

However, you might want to consider keeping it on R. If it is not a high mileage bike that you need to do 1000's miles between changes that is. R is still a fantastic oil IF its used correctly. It is like treacle cold, so must be warmed up prior to thrashing... It breaks down if 'boiled' so must be changed if this occurs which is unlikely on a road bike (a single I assume)... It absorbs moisture so must be dumped if left stood in cold / damp conditions... It breaks down relatively quickly, so not suitable for super high mileage machines. But... between those parameters its lubricity and film strength are (I believe this is still true) unbeatable.

Yes its expensive , but all good oil is, and you'll most likely only need to change it once per year. And its possibly a cheaper 'total cost' option, the lack of wear of engine components in race engines run on R is impressive.

The bigger question, as already posted, is the possible 'gumming up' internally. I'd have a good look inside covers etc to see what is like, if it looks clean, I'd give it a go 'as is'. And personally, if its an 'occasional use only' fun bike, I'd keep it on R.

Jus' my twopenneth.

Castor based racing engine oils usually have a VERY short working life - only a few hundred miles usually - , so you'd be dumping it out and putting in fresh so often as to not need an oil filter ?? Thats why it works so well, after all.....

Depends on what engine and what castor based oil too.
I've cleaned out an engine from way back that had a thick rubbery gooey coating inside, that took considerable cleaning out.
An engine flush is not going to remove that in one go, you'd have bits still coming out decades later ?!
NOTHING dissolves baked on castor oil easily......

+1 Rohan

Thanks for the replies chaps.
The motor is a BSA Victor Special 441 single, that has only done approx 150 miles since a thorough and proper rebuild. After looking at the replies I think my plan will be to stay with the Castor oil (Silkolene Castorene R40) and try and snug in a Magnefine filter if possible. I won't be flushing the motor and changing to a "normal" oil as I just don't trust the process to remove all the castor, that can wait till I ever rebuild the motor.
cheers
sam

trident sam said:

Thanks for the replies chaps.
The motor is a BSA Victor Special 441 single, that has only done approx 150 miles since a thorough and proper rebuild. After looking at the replies I think my plan will be to stay with the Castor oil (Silkolene Castorene R40) and try and snug in a Magnefine filter if possible. I won't be flushing the motor and changing to a "normal" oil as I just don't trust the process to remove all the castor, that can wait till I ever rebuild the motor.
cheers
sam

Click to expand...

I know of no reason why flushing out all the bean oil would be in any way critical. Oils mix as long as you're not changing viscosity and even then it's not a big deal. By the time you get a couple of oil changes down the road, all the old oil would be gone anyway if you're using detergent oil and a filter.

While MODERN castor oils will mix * with mineral oils,
the old type castor based oils were VEGETABLE oils, and would NOT have anything to do with mineral oils.

Like the old saying - oil and water don't mix....


* use with caution - not all caster based oils will necessarily mix with mineral oils,
some are still pure bean oil, and keep entirely to themselves.

Mixing them with anything else oily could be a complete disaster.
There are plenty of old time stories of this...

Hi Rohan,

So are you saying modern castor oil (more polar) will not mix mix with old water based castor poils (non-polar?)

This is getting interesting...

Rohan said:

While MODERN castor oils will mix * with mineral oils,
the old type castor based oils were VEGETABLE oils, and would NOT have anything to do with mineral oils.

Like the old saying - oil and water don't mix....


* use with caution - not all caster based oils will necessarily mix with mineral oils,
some are still pure bean oil, and keep entirely to themselves.

Mixing them with anything else oily could be a complete disaster.
There are plenty of old time stories of this...

Click to expand...

I don't know about that - with all the varieties of castor that seem to be about these days.
It seems to getiing more user friendly, recently.

Its whether they will mix with mineral oils or not, that is of prime interest here.
Once upon-a-time, that couldn't be taken for granted.
So shouldn't just be taken for granted....

You hear of engine disasters back then.....

Sam,

Silkolene and Morris both do synthetically enhanced castor oils these days, claimed to maintain the benefits of R whilst minimising the traditional down sides.

I'm sure they're both good, I have good personal experience with Morris.

If you check them out I'm sure your mind will be put at rest about using R.

Heck, if I wasn't such a Redline fan I'd even consider using it myself!