Used engine oil

Post by **Mick_Anik** » Mon Aug 31, 2009 1:24 pm

A few years back I heard a BBC programme on the subject of engine oil for cars. One guy was talking about the marketing propoganda surrounding engine oil.

He was some kind of oil expert, and his opinion was that old engine oil, if cleaned of any water, bits and other impurities - traces of antifreeze or petrol perhaps - was just as effective as new engine oil. To paraphrase him....."Oil is oil; it lubricates. It reduces friction between two surfaces. New or old, it does the job".

Any thoughts on this opinion?

Post by **Peetee** » Mon Aug 31, 2009 2:42 pm

It's nonsense. Oil is composed of chains of molecules specifically refined and processed for the job in hand. Like any petroleum based product external influences cause these molecules to break down and become much less efficient. look at what happens to supermarket bags if left to the elements. it's the same problem. I wouldn't trust cleaned oil to protect my engine any more than I would trust a 2 year old plastic bag (that I've used to keep my tools dry) to get my bottles of wine home.

Post by **katy** » Mon Aug 31, 2009 4:45 pm

The oil itself may be OK, but it's the additives that break down, deteriorate, wear out and change that is the problem.

Post by **MarkyB** » Mon Aug 31, 2009 6:10 pm

Don't the long chains get broken down too?
More so in the gearbox but it must happen in the engine too.
The idea of just filtering it sounds simplistic.
I wonder if the expert worked for an oil recycling company?

It might work better with cooking oil but I doubt it or chippies wouldn't get through so much.

Post by **Mick_Anik** » Mon Aug 31, 2009 8:47 pm

I can't remember who 'he' was, but I always think of it when I change the oil, which I do on time, if not early.

His argument was that there is 'lubrication', and there is 'no lubrication'....it is either present, or it isn't. As to say, like with water, something is wet, or it is dry. Anything which isn't dry is wet, to a degree. If there is lubrication ie a film of oil between the surfaces, then it is lubricated. If not, it isn't.

I don't really have an opinion as I know nothing about the properties of engine oil, except that it's nice when the oil is your engine is still of a light colour and clear even after several thousand miles

.

Post by **Peetee** » Mon Aug 31, 2009 8:53 pm

His argument was that there is 'lubrication', and there is 'no lubrication'....it is either present, or it isn't

Well water would lubricate two adjoining metal surfaces but it would do nothing for the protection!

Post by **ColinP** » Tue Sep 01, 2009 12:52 pm

Engine oil has to perform several functions:-

1) lubrication
2) cooling
3) carry away "bits"
4) be able to form thin films - even under very high pressure (ie the film has to remain intact)
5) absorb some water
6) remain able to do all of that after 12 months' use...

Check out the API specifications for oil - they include lots of topics.

The gearbox is actually a much easier environment - the molecules won't get broken down by mechanical forces (carbon - carbon bonds are just too strong) - most of the breakdown is caused by the heat and chemical contamination from the combustion of the petrol.

Obviously, some oil is better than none - but if your lubrication of (e.g.) the big ends fails because the oil film breaks down under pressure, then lubrication goes to no lubrication very quickly...

Colin

www.xing.com/profile/Neil_Shorney · Post by **hornmeister2000** » Tue Sep 01, 2009 1:24 pm

I think to say that "there's lubrication or there's no lubrication" is ridiculously simplistic - some oils are thicker than others, you could lubricate with WD40 if you wanted but it wouldn't do your car any good. Only the best oil for my cars, I'm afraid. I use Magnatec 10W-40 in my Laguna, Formula-RS 0W-40 in my Maestro and Halfords or Castrol Classic 20W-50 in the Minor, never had a problem, and "if it ain't broke, don't fix it"!

Post by **MarkyB** » Tue Sep 01, 2009 7:41 pm

I think the term 'pundit' applies better the expert.
He had an axe to grind, or he was talking from a sub prime orifice

.

Post by **Mick_Anik** » Tue Sep 01, 2009 8:37 pm

Well, it seems all comments here are spot on - from a thorough browse around it becomes apparent that viscosity (oiliness) reduces with a working oil's age. Thus, the level of parts protection is reduced.

Views differ a little on exactly how often engine oil should be changed, but changed regularly it should be!

A nice find here:

http://www.carbibles.com/engineoil_bible.html

A lot of stuff about cars, by a chap who seems to have looked into the subject extensively. The link takes you to the oil section......more sections in a drop-down menu on the left of the page. Great for newcomers to car maintenance.

A further area of possible discussion - the positioning of a certain type of magnet (definitely not fridge!) on a screw-in canister type of oil filter, or on (or in) the sump, to catch the micro-particles which the filter misses. This is discussed towards the end of the oil section page.

There's no end, there really isn't!

Post by **MarkyB** » Tue Sep 01, 2009 9:00 pm

Whoa, hold on now

.
A nice find is the 'bible' with an advert at the top?

I don't think so.

The 'which oil is best' thread leads to lots of discussion and diffenent opinions on many car forums.
But here we are fairly agreed that even the cheapest, nastiest 20/50 is better than the oil the engine was designed for.

It can be a can of worms but now the most likely response is *yawn*

Post by **Mick_Anik** » Tue Sep 01, 2009 9:17 pm

I feel it's unfair to dismiss a web page because of an illustration of an outdated oil can. The page has a picture of a Bosch oil filter, too. But when you look at the sheer length of the page, the space taken up by these illustrations is minimal.

In the brakes section, there is an illustration of a braking system, and you can see the name "Siemens". And that's about it, on what is also a very long page indeed, packed with useful information unrelated to specific manufacturers.

Oops! Just realised I've just done a freebie for Siemens.

Post by **paulk** » Tue Sep 01, 2009 9:52 pm

Oops! Just realised I've just done a freebie for Siemens

Girling,Lockheed, Ferodo

Other makes are available ;)

(s'alright Mick I think I've got you covered)

Post by **MarkyB** » Wed Sep 02, 2009 9:02 am

OK, it isn't a bad site but having a picture of one companies product at the top spoils any feeling of impartiality for me.

I like the hard drive magnet idea so much I'd already done it.

Post by **Peetee** » Wed Sep 02, 2009 9:51 am

I like the hard drive magnet idea so much I'd already done it.

Might be a good idea for the gearbox too. If you could find some way of attaching to an alloy housing.

Post by **bmcecosse** » Wed Sep 02, 2009 2:42 pm

Oil which has been correctly 're -manufactured' will be fine for Minor engines ! It should have been throroughly filtered and treated wuth heat under vacuum to remove all traces of unburned fuel and moisture. Then new additives and a proportion of 'new' oil added to bring the final product up to the required spec. I have no qualms about using Asda/Morrison etc budget oils (which are very likely re-manufactured) in my A series (and TR7) engines - but I don't put it in my modern Vauxhall or Renault engines!

Post by **MarkyB** » Wed Sep 02, 2009 6:04 pm

Might be a good idea for the gearbox too

Isn't the drain plug 'hollow'? easy enough to saw a bit off the magnet and stick it in with some epoxy glue.
Not that it would be likely to go anywhere, it's quite easy to end up with blood blisters playing with magnets that powerful.

Post by **Mick_Anik** » Wed Sep 02, 2009 7:53 pm

I remember seeing a magnetic drain plug, and it was certainly on a Minor or something related, as I always had BMC type cars when young.
Whether it was on the engine or gearbox, I don't know, but I suspect it was the gearbox.
I supposed after forty years the magnetism may go west, though.
With a gearbox dismantled, one could drill a small hole in the magnet and in the casing, and mount it inside with a gasket and a nut, bolt and washers. This would ensure it wouldn't come loose.

It's great the way threads can develop.

Post by **Peetee** » Thu Sep 03, 2009 8:54 am

the magnetism may go west

I can see the headlines now "Ten Thousand Scouts Reported Missing as Exhausted Racing Pidgeons Drop From Sky"

Post by **Dru** » Thu Sep 03, 2009 11:31 am

My MZ had a magnet on the drain plug. Looked like a little hedgehog sometimes, when I took it off

Talking 'alternative' lubrication reminds me of an engineer on Sealink Isle of Wight, who described how a Voith-Schneider propulsion unit developed such a bad oil leak that they gave up on oil and ran a fire hose into the gearbox for the trip to the shipyard...