Oil change is often advised 'every year or x miles, whichever comes sooner.'
I haven't changed mine for three years 'cos I only do a few thousand a year and the revs rarely go above 2500 [Italian tune-up every 1000 miles or so when warm to flush the oilways]. It's six years old in my TR7 which only does a few hundred miles a year.
I inherited a 3-in-1 can which is at least 40yrs old, and it still contains oily fluid which seems much the same as that in my new can.
Can any engineers or chemists persuade me that my engines might be wearing out too quickly? Could it improve with age like certain wines?
Made make/model non-specific.
Edited by Pugugly on 25/06/2008 at 22:14
|
Could it improve with age like certain wines?
Absolutely ! Leave it in there long enough and you'll be able to drain it and put it straight into the petrol tank.
Long life oil and a free gallon of petrol at the end. How much greener can you get ?
Just out of interest, does the anti-freeze or brake fluid ever get a look at ?
Do you ever change the filters ?
Edited by gmac on 25/06/2008 at 22:27
|
Isn't mineral oil already millions of years old when it comes out of the ground?
Mercedes seem happy for the fully synth oil to stay in my car for 2yrs - I do wonder what it looks like though - there's not even a dipstick to allow me to feel it.
|
|
|
If this isn't a troll....
Oil doesn't really go off on it's own.
However, if you leave it sat in an engine that never gets hot, then the acids from combustion and blowpast will fester in the oil, slowly eating shell bearings and the like.
|
|
John, How come your advising on the best way to remove an oil filter in your June 19th post ;)
|
|
`You`re`, I mean..;)
|
On June 19, John F posted: 'A long piece of rope, just under 1cm diam. Clean oil off filter casing. Wind neatly round and round and round.....starting from bottom working up to where attached. Pull hard - if you get enough coils on it won't slip. If it does, sand-paper it and try again.'
A case of the cobbler's kids never shod?
|
|
|
|
John How come your advising on the best way to remove an oil filter in your June 19th post ;)
Just a hopefully helpful response - it was years ago on our old Passat 2.0GL and I remember there was no room to get a grip on it any other way.
Doesn't look as though anyone has persuaded me to change yet.....I love the post about transferring 3K-mile-old oil straight to another engine!
|
|
|
|
Oil doesn't really go off on it's own.
I'm pleased to hear that. Since my car hardly ever needs topping up between services my topping-up can is now quite a few years old.
|
I doubt that it would go off, but my bigger concern would be the build up of moisture and acids, especially if the car is being used for low mileage. My Supra does low miles but I change the oil every year at a minimum - a quick oil change doesn't cost much.
|
Engine oil, when old, will lose its lubrication characteristics gradually [because of its molecular structure].
That's why regular oil change is recommended.
However, some people still think changing oil is same as topping up to maintain level!
Theoretically, engine oil should not go off by its own - but various factors (eg. weather, engine heat etc.) may cause very very minute quantity of oil to vapourise which is not unusual.
This site [www.carbibles.com] has an excellent explanation on this.
Edited by movilogo on 26/06/2008 at 09:59
|
|
|
|
|
Just out of interest does the anti-freeze or brake fluid ever get a look at ? Do you ever change the filters ?
Coolant never gets changed - the only time I changed the TR7's was when I had to recon the rad after a huge stone chip pierced it about 20yrs ago [the primitive way councils repair country roads using the public's cars as free rollers...I felt like taking ours to the small claims court just for the hell of it..]. When I had to replace the leaky water pump about 5yrs ago I collected the coolant and filtered it before putting it back. After 28yrs the heater matrix is still original and there has been no other incontinence [ the head has never been off - it is probably immovable by now!] so I reckon my theory that once the oxygen in the coolant has been used up corrosion will virtually cease might be correct. Occasionally put sample in freezer just to check...
Brake fluid - certainly no more frequently than 5-10 yrs. I am not in the habit of tearing down
Alps or harsh braking at frequent roundabouts.
Oil filters - every 10,000m. Air filters - never, but occasionally inspect and brush/vacuum as much of the outer side concertinering as I can get at.
|
Brake fluid - certainly no more frequently than 5-10 yrs. I am not in the habit of tearing down Alps or harsh braking at frequent roundabouts.
Brake fluid is hygroscopic and (assuming you are in the UK) you live on an island at the edge of an ocean where the air is naturally damp.
|
|
|
|
|
|
I heard a story some time ago that a WW2 bomber was lifted from the sea somewhere around the coast, and the oil in the engines and prop-governors was still in spec 50 years on ! So I would suspect that modern engine oils should keep indefinately.
|
There was a recent report of a newish MB with a broken engine. Coincidence or not, its oil had not been changed in the 45k since new. In contrast, the drivers of million-mile MB taxis take pride in frequent oil changes.
Everything degrades with time. Given the punishment suffered by oil -- the more so when a car is not used frequently -- it's hardly likely to be exempt from this universal process.
I cannot for the life of me fathom the thinking that goes against all expert advice and takes some sort of pride in making oil last an unreasonable length of time. If ever there was a false motoring economy, that's surely it.
Take a look at FAQ 14 and any other of the many sites with advice about oil.
|
|
|
So I would suspect that modern engine oils should keep indefinately.
Don't they abosrob moisture from the atmosphere and loose some of their lubrication properties?
|
IIRC Oil molecules break down under the influence of heat and load.
In a can it should be OK for a few years. In an engine it will degrade - why take the chance?
|
Used engine oil is normally recycled, cleaned and later sold as the cheaper oils you find in motor parts and supermarket outlets.
|
I have a friend who is so tight, that he only ever changed his car oil when i did mine, (i changed mine every 3000 mles) all he ever bought was a new filter, and he begrudged buying that! the oil I drained from my engine, went straight into his without even having chance to cool down.
Having said that, it does mean that the oil even after he had used it, was only 6000 miles old, still well in "spec" i would imagine, so maybe he wasn't "tight" as such, - just sensible?
Billy
|
|
Back in the '70s i was running an old Hillman Minx as a second car that consumed oil at about 50 miles per pint, all out the exhaust. I started using GTX in my first car, and put the used oil in the Minx. The Minx slowly improved to about 500 to the pint!
|
I think the answer to the OP is No, it probably doesn't go off if left in its sealed can and not used...
But if its in an engine in a car then yes it does, and low mileage can be harder on an engine than high mileage as it involves more running when cold and probably more stop start work... and the engine may not even get up to running temperature.
As someone else said, its false economy not to change it regularly, after all, whats £20 a year against the cost of a new engine?
|
My current car is a diesel (VW Passat TDI, high mileage) So I do fairly regular oil changes - not as frequently as the manual says, but in the same order of maginitude.
Before, with petrol vehicles, I seldom did oil chages - just occasionally when I felt like it.
Some years ago, one luxury car maker did a test on one of the vehicles in its car pool / press demo fleet.
This test involved not changing the oil at all. At the end of the test the engine was stripped down and found to be in no worse condition that one which had received regular oil changes.
|
Some years ago one luxury car maker did a test on one of the vehicles in its car pool / press demo fleet. This test involved not changing the oil at all. At the end of the test the engine was stripped down and found to be in no worse condition that one which had received regular oil changes.
Without doubt an un-biased test, with no 'bomb-proof mechanicals' marketing spin.
|
|
|
|
As someone else said, its false economy not to change it regularly, after all, whats £20 a year against the cost of a new engine?
As someone [ number cruncher?, aprilia? ] has said, it is virtually unknown nowadays to find an engine has failed due to quality of oil. Known problems [ eg.such as Vectra C chains failing] are usually traced to component design problems rather than the oil used.
Has anyone come across VW PD engines suffering failures due to wrong type of oil being used?
Modern fully synthetic oils are not prone to the degradation that conventional fossil oils used to suffer from.
|
|
If you were so minded, you could send a sample off for analysis - it's all the rage in the US and there are a few companies in the UK who do it.
|
>>send a sample off for analysis
It sounds like a good idea doesn't it?
The problem is that you get back a list of numbers about the oil - it's soot content, the contents of various engine wear metal types, the presence or absence of glycol, and more esoteric values like total base number, a whole page full of numbers! Now, I'm as big a fan of quantifying things numerically as you'll find, but, the problem is that manufacturer's don't publish any sensible way to interpret these values - so, you're left with rumour and spurious conjecture to guide your interpretation of these complicated data.
The usual smoke and mirrors offered in these cases is to ask for a sample of new oil, and then compare the degradation compared with the as new condition of the oil. But, of course,one would hope that brand new oil will be better than required, and comparing with new oil isn't really meaningful when what you really want to compare against is a well defined criterion of adequacy.
After paying for the analysis, you're still on your own when you ask the question of "when should I change the oil?"
|
|
Quote:....."Without doubt an un-biased test, with no 'bomb-proof mechanicals' marketing spin."
Re. the test by the luxury car maker that found not changing the oil had no harmful effect on the engine.
This was told to me by someone who had worked for the company involved. It was an internal test that was not publicised. I can't remember why it was done but I think one of the engineers had a hunch that oil didn't need to be changed regularly (these were petrol engines). Also they'd had occasional problems with owners not having their cars properly maintained and then complaining about faults, despite being an up-market brand. Maybe they wanted to see how much neglect the engine could withstand.
|
|
|
Modern fully synthetic oils are not prone to the degradation that conventional fossil oils used to suffer from.
Must have missed that, I didn't see where it said he'd used fully syn....
|
|
|
|
|
|
|
Saving money is a good idea, John.
I save money by never changing the cooking oil in a frying pan.
It starts off as a clear, translucent, yellow fluid.
After 2 or 3 sessions, it changes to a mucky, opaque, brown fudge (when cold).
After 6 or 7 sessions, it becomes a squalid blacky-brown tar garnished with charcoaled fragments of the last week's fry-ups.
I love the taste of charcoal-dashed fried eggs - the taste of saving money!
And, you know, in a very real sense, car-engines are just like frying pans!
|
>>And, you know, in a very real sense, car-engines are just like frying pans!
Really? In what way is this?
|
car-engines are just like frying pans! Really? In what way is this?
Made of iron. Covered in dirty old oil and calcified burnt stuff. Gets hot when used and then goes cold and greasy. Impossible to get properly clean.
On the other hand, a bit heavy and awkward as an improvised weapon for whomping some tiresome person upside the head. You need a proper skillet for that.
|
Pop a rasher of bacon inside the oil cap and it will be nicely done after 10 miles.
Eat it with the toast made by wedging slices of bread in the exhaust manifold.
Why pay caff prices when you can cook your own?
|
|
Perhaps HJ should change his answer in the Q&A section where he mentions regular oil changes in view of the above discussion, as it seems that they aren't required at all! ;)
|
Many thanks to all for your responses
<<
I cannot for the life of me fathom the thinking that goes against all expert advice >> -Roger, above....
The trouble is that some so-called 'expert advice' is thoughtless dogma passed without question from one generation to the next.
So far I have read nothing to convince me that I need to waste time and money changing oil just because it has been sitting in a virtually sealed engine sump for over a year, which is reassuring.
|
|
Except that the contamination comes from within the `virtually sealed sump` and what`s going on directly above it, rather than outside?
Edited by oilrag on 27/06/2008 at 18:58
|
Except that the contamination comes from within the `virtually sealed sump` and what`s going on directly above it rather than outside?
But in low mileage engines nothing actually is going on most of the time. Last year the oil just sat there for 8660 hours out of 8760 hours. [3K miles at avr 30mph]
|
Hi john
I bet a lot of us `oil changers` would love to see the results of an analysis of your engine oils. ;)
I mean that in an interested, non critical way too.. tempted to prove your point? I think Millers may do an oil analysis..
Anyway, just for the benefit of a compulsive oil changer like me, what oil have you got in there?
Regards ;)
|
>>would love to see the results of an analysis of your engine oils
Why? What would seeing this allow you to say? What would be the criterion of acceptability? Who defines this acceptability?
|
Why? What would seeing this allow you to say?
I second that. I think there is a lot of "oils musts be changed at X thousand miles or every year" etc. without any evidence to back up the statements.
The only incident I know of where poor condition of oil caused damage: It was a Triumph Dolomite Sprint with a water pump where the seal had been weeping and allowing water to leak in to the engine, and without the owner realising it, the engine had been running on "mayonnaise". This led to big-end bearings getting worn, and that was it - no other damage was found. Thinking of it, I have not heard of big-end bearings failing on any car for many years now.
|
Anyway just for the benefit of a compulsive oil changer like me what oil have you got in there?
Ford 10-30 in the A6......was on offer in local Wilcos, 10-40 in the TR7 - can't remember what, but decent make - I don't risk the really cheap stuff....... was brought up to buy the best, make it last!
|
|
|
