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Soluble oil as coolant

Posted: Thu Aug 23, 2018 7:44 pm
by Lofty
I’ve just had my radiator cleaned out and the guy advised me to use soluble oil instead of coolant. He said it’s kinder to old engines. Anyone have experience with this?

Re: Soluble oil as coolant

Posted: Thu Aug 23, 2018 10:32 pm
by GeoffDEAL
Hi not so much experience as i brought a 990 that has engine oil as the coolant, i was told the previous old owner found a solution to water in the oil he replaced the coolant with engine oil apparently worked on light duty for years and still the same when i brought it to restore. Will try it and see how it goes but would think it would be a problem if it did normal hard work as oil does not have the heat exchange rate of water, but for light duty possibly fine, if i give it a complete rebuild the liners should be easy to get out ! This is only the second time i have ever heard of oil as a coolant others may know more.

Re: Soluble oil as coolant

Posted: Thu Aug 23, 2018 11:14 pm
by Lofty
Thanks Geoff. To be clear soluble oil is added to water in a small amount, not used neat. Pure engine oil is a new one on me!

Re: Soluble oil as coolant

Posted: Thu Aug 23, 2018 11:48 pm
by cossyrec
second go at this post. many years ago we bought a S/H Scania 110 super from Sweden when the changed from RHD to LHD it was mint. we converted it to a recovery vehicle gave it a service and painted it. within weeks all the paint on engine and gear box started blowing of anywhere dissimilar metals touched braided earth straps lasted about a month aluminium cluch air assisted pack seized up solid. it became a nightmare. we mentioned it to an old fitter at the Scania agent he told us don't know the cause but the answer is cutting oil (suds) as used in machine shops in radiator coolant. we put a small amount in. it stopped. told us he learned trick ww11 working on generators. many years later heard it was static electric build up caused by fanbelts Still don't know

Re: Soluble oil as coolant

Posted: Fri Aug 24, 2018 12:00 am
by cobbadog
Yep, I remember Dad putting a small amount of soluble oil in the radiator of his old car and I can only guess this was for lubricating the bearing in the water pump. I only run glycol in our vehicles especially at the times when there are frosts about. Don't know if soluble oil stops freezing so I would be careful.

Re: Soluble oil as coolant

Posted: Fri Aug 24, 2018 10:50 am
by skyrydr2
It will freeze up , so be sure it is still mixed proper with a proper anti-freeze to water ratio.
As for engine oil as coolant? Hmmm........
I'm not sure how good the water pump would do circulating it through the radiator on a cold morning?

Re: Soluble oil as coolant

Posted: Fri Aug 24, 2018 1:16 pm
by Lofty
I asked the radiator guy if there was any disadvantage and he said none. But I found a couple here: https://www.hcvc.com.au/forum/oldjunk/3 ... tors#43183

The manual is not much help on this, though it did say that any coolants must be formulated for diesel engines.

Freezing is a non-issue where I live.

Re: Soluble oil as coolant

Posted: Sat Aug 25, 2018 6:48 am
by cobbadog
Did your radiator guy say why he doesn't use anti-freeze or rather suggests you use soluble oil? I would only use what I know works, anti-freeze. It is a similar thing when I was rebuilding the 30C engine. DO I put the cooling tube in the head or not. So many say no they would not and there is no need for it. I found a guy locally that makes them from stainless steel and for the price I bought one and fitted it. We have done many tractor treks in some rough country up and down mountains high revs and low gears and the engine temp sits rock solid always. In fact I cannot get the gauge to register with the blind all the way up and the tractor sitting still in any rev range. But once I start driving it comes up to normal and stays there.

Re: Soluble oil as coolant

Posted: Sat Aug 25, 2018 7:09 am
by Lofty
cobbadog wrote:
Sat Aug 25, 2018 6:48 am
Did your radiator guy say why he doesn't use anti-freeze or rather suggests you use soluble oil?
He thinks modern coolants formulated for alloy motors can cause corrosion in old iron ones.

Re: Soluble oil as coolant

Posted: Sat Aug 25, 2018 8:53 am
by rid54
Lofty wrote:
Sat Aug 25, 2018 7:09 am
cobbadog wrote:
Sat Aug 25, 2018 6:48 am
Did your radiator guy say why he doesn't use anti-freeze or rather suggests you use soluble oil?
He thinks modern coolants formulated for alloy motors can cause corrosion in old iron ones.
I do think that is a bit far-fetched. The corrosion risk in modern engines with different materials (alloys) in different parts of the coolant path, comes precisely from this mix of materials. Some kind of self-electrolysis can appear, as if the engine as a whole were a kind of battery. The anti-corrosion additives prevent this unfortunate process. It is unlikely, that the modern coolants should cause problems in an all-iron engine (after all, there are still iron parts in modern engines too).

Re: Soluble oil as coolant

Posted: Sat Aug 25, 2018 9:40 am
by broadsword
A lot of the modern coolants were used when you were mixing iron blocks with alloy heads and also new style alluminium radiators. VW keep changing their coolant specs but they were using cast iron blocks for a long time (same as Ford on the old 1.8TDI engines).

There is a bit here that says one of the issues with very modern coolants is they can attack brass in older systems and also solder.

https://www.wolflubes.com/EN_EU/Blog/20 ... olant.aspx

Re: Soluble oil as coolant

Posted: Sat Aug 25, 2018 2:30 pm
by rid54
...and furthermore, cylinder liners are still cast iron as far as I know. Dry liners aren't very common, so I guess there's iron in the coolant stream even in modern engines.

Re: Soluble oil as coolant

Posted: Sun Aug 26, 2018 6:50 am
by cobbadog
Yep there is electrolysis happening in all our engines. When a new radiator is fitted it should be tested and if required an extra earth strap fitted usually helps the issue. However, this is nothing new and is why welsh plugs are made of steel so they rust out and not your block. They act as a sacrificial anode and do the job beautifully. I avoid using brass welsh plugs for this reason, unless it is in a hard area to access easily to replace like the welsh plug at the rear of a Holden grey motor head.
So I would still stick with a coolant over soluble oil.

Re: Soluble oil as coolant

Posted: Tue Sep 04, 2018 9:42 pm
by bedwards1966
Modern coolants (like OAT) are not suitable for our old machines which is a shame as they don't need changing as often.

I have no personal experience of using oils as a coolant but I have heard of it damaging rubber hoses.

I really don't see what is wrong with using the correct Ethylene Glycol antifreeze and changing it every two years. I'm sure that most cooling system problems - blocked radiators, corroded liners - are a result of not keeping the corrosion inhibitors up to date. Or worse still, running plain water 'because it's summer'.

I'd take basic maintenance over unknown alternatives. Frankly, I think that if they were sensible options manufacturers would be using them already...

Re: Soluble oil as coolant

Posted: Tue Sep 04, 2018 10:00 pm
by rid54
Can only agree with above. Keep to established practice unless some definite benefit is known to be had from alternative ideas. One good idea, though, is to use distilled/de-ionized or rain water in the coolant together with 50% plain vanilla ethylene glycol. The absence of minerals (in the shape of ions) and oxygen in the water, will help inhibition of corrosion.

Propylene glycol may be used instead of standard ethylene glycol; it is a bit less poisonous to animals and a bit more environment-friendly. It works just as well using the same mixture proportions, but care must be taken to avoid mixing the two anti-freeze chemicals - use one or the other.

The more advanced anti-corrosion schemes (HOAT and whatever) are brought into the market to deal with engines with alloy parts (light-metal heads and such); they're not intended for all-iron engines at all. They don't cause problems, but they don't fill their purpose in an all-iron engine.