Snake oil for cars engine

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Oil is aged by shear-thinning, condensation, fuel contamination to name a few. That's why it's not just a marketing ploy to recommend frequent changes.

Part of my career was managing the lubrication programs in the manufacturing plants in which I worked. I have some education in this, though maybe enough to be dangerous...

In the absence of outside contamination (water, fuel, adding the wrong fluid to the sump), the useful life of motor oil is really about the additives, not the oil itself. Well-refined (or even better synthetic) base oils don't really degrade to any great degree.

Shear thinning is a degradation of the long-chain viscosity modifiers in a multi-grade oil. That may take some explaining. An oil rated as a viscosity 5W-30 is a 5 weight oil (weight in this case actually being a measure of viscosity) with added polymeric additives that 'unfurl' as the oil warms up and counteract the oils tendency to thin with increasing temperature. So, the oil acts as the 5 weight oil that it is on cold startup, but like a 30 weight oil when up to temperature. If the viscosity modifiers physically break down over time, the oil will not maintain viscosity at high temperatures.

Detergents in oil help prevent varnish buildup, and neutralize acids formed as combustion byproducts. They are sacrificial, once the detergent in the oil has neutralized all the acid it can the metal surfaces are no longer protected from attack by those acids.

Dispersants keep soot particles suspended in the oil, and actually help tiny particles to clump together so that they can be removed by the filter. Once all of the dispersant has been filtered out the soot will just continue to circulate and cause wear.

The only way to know if the additive package in your oil is depleted is by lab analysis. There is (was?) a guy out there on the web that was running a long-term experiment on his own car. Every 5000 miles (?) he was changing the filter (to remove the physical contaminants), topping up the oil lost to the filter change and sending a sample off to a lab for analysis. Over tens of thousands of miles, the oil analysis never said he needed an actual oil change. The top-up oil from the filter changes gave him enough fresh additives to maintain protection. His lab tests were paid for by folks contributing to the website, so that may not be cost effective for most of us.

I drive a diesel Benz, use the factory-approved oil (Mobil ESP, which is apparently sold by MB under their own label as well), change it on the factory schedule and don't worry about it other than that.

Bill
 
The primary killer of motor oil is short trips where the oil does not get warm enough to evaporate water and blowby gases that go into solution in the oil. Most oil life monitors work by accumulating engine revolutions in bins as a function of estimated oil temperature. If most of your operation is short trips at lower temperatures the oil degrades faster, if it's extended driving with a fully warmed up engine the oil lasts much longer. The taxi example cited earlier is a case where the engine is rarely stopped so very unlike typical usage. If you have an oil life monitor follow the recommendation for changes. If you don't and you are a short trip driver change frequently at 3,000-5,000 mile intervals. If you're a long trip warmed up engine driver 7.500 to 10,000 mile intervals are fine.
 
Filters go bad in about a year. Change the filter or change the oil (and filter) yearly, or by miles, is definitely the best. I can't confirm that all cars can just change the filter and top off like stated above... so I can't actually recommend that. But I have seen cases where super filtration was used and they never needed to change the oil - several filters, not just the one, usually with a bypass filter.
 
Filters go bad in about a year. Change the filter or change the oil (and filter) yearly, or by miles, is definitely the best. I can't confirm that all cars can just change the filter and top off like stated above... so I can't actually recommend that. But I have seen cases where super filtration was used and they never needed to change the oil - several filters, not just the one, usually with a bypass filter.

I forgot to do a yearly oil change on one of my cars. I didn't put much milage on the oil, but I ended up going two years between oil change.
It has a cartridge filter from a good quality brand (Probably Mahle or Bosch). When I removed the filter it started cracking. After removing it from the engine, I squeezed it a little. The whole filter collapsed and smuldered into thousand pieces.
If that happened inside the engine It would probably clog most oil passages.

Now I'm extra aware of time spent between oil changes. I don't want to see another filter in that condition again.
 
Note that manufacturers commonly make different filters for long change and short change intervals using different filter media. For example, there are two different Purflux branded (OEM maker) filters specified for my Peugeot GTi, one with a paper type element and the other, a polymer type for longer change intervals.
 
Disabled Account
Joined 2019
Should we glue to SAE or try to do better according our car use ?

Hi,



Now I know I should indeed change the oil (thanks all for the inputs)



Is there please a good enough difference between a 0W30 VS a 5W40 when driving very small distance (less than 30 km for instance or even less) or urban cycle ?


having a 5W40 oil grade in the constructor manual and a diesel with no FAP, I more and more took plubic transports and sometimes don't drive for 2 weeks and then just drive smal distance. I know the first grade at 0 will be fluider than 5 for protection at starting for the dry cylenders but the second grade at 30 will be better for agging of the parts but maybe not good enough for etancheity ?


I even see 0W20 oils comming (I bet about fighting against pollution and decrease fuel cunsumption) ?!
 
Disabled Account
Joined 2019
Thank you. I also surmise the 5 grade stick a little more to the cylenders than 0 grade after one or two week rest ...


I asked myself cause I see know most of the compact diesel going with such zero winter grade and also fluider oil then hot. But I really surmise it's about targeting less CO2 emission and fuel cunsumption reduction norms!
 
The mechanical elements of a car that act with metal-metal contacts (like the cardanic ends of semiaxes, cylinders and rings, bearings of cranks and banks, gearboxes and transmission, etc) are highly protected with the only effective antifriction additive .
It is composed of molybdenum disulfide, you can see an experience witnessed by the fivefold Argentinean world champion Juan Manuel Fangio, in the attached video.
The vehicle traveled 30 km with only Molykote in its oil pan! Without any damage.
It forms deposits in the metal structure, which turn it into a "soapy" surface, a crude example that I find to graph the effect achieved.
It can save the moving parts of the engine from destruction still working in extreme cases of total loss of oil, obviously for a short time.
In a local automobile factory, in the assembly line of the cylinder caps, operators reported (this was long before the current robotization) that the bolts were cut by applying the adjustment voltage recommended by the manufacturer.
The bolts were returned to the manufacturer and a new provision was requested.
But, the problem continued, and after arduous technical research on tempering and bolt material, the manufacturers of the bolts decided to observe live and direct the work of the operators in FMC.
It was seen that the bolts were lubricated before being installed and adjusted in their housings, but someone had changed the conventional grease drum that was used in the assembly line by a Molykote drum!
Then, the tightening force of the bolts was much higher than recommended, due to the antifriction effect of the "lubricant", causing the breakage.
So I use it from that moment, this episode was told to me by an engineer who worked there.
It is suitable for mineral and / or synthetic oils, engines powered by naphtha or diesel, with or without a turbocharger.
I do not own shares of the company nor do I have any personal interest in promoting this product.
Just a recommendation, take it or leave it .....:)

YouTube

MOLYKOTE™ A2 Turbo | Molysil
 
Disabled Account
Joined 2019
Chemestry looks like a complex thing and oils are developped for precise uses from what I read. Aditives in engine oil should be good as well. Plane engines oils must be something.
Nowadays what collapsing first is around the engine but development faults. My car has an engine fragility involving bearing clush and engines break as soon as 100 000 km...:nod:
Well I drive lesser and lesser and soon it will be cheaper to rent sometimes a car than a car which can stay two weeks in the garage.
 
Last edited:
IMO engines have never been better in terms of efficiency and reliability. Nevertheless my wife's Alfa Giulietta used 1 litre of oil per 1000 miles for the first 10,000 miles. After that, it suddenly seemed to use little oil at all!
Of course during the high consumption period we complained like hell and my wife being the rottweiler she is, even found a contact in Italy who pacified us by supplying a paid short holiday!
 
IMO engines have never been better in terms of efficiency and reliability. Nevertheless my wife's Alfa Giulietta used 1 litre of oil per 1000 miles for the first 10,000 miles. After that, it suddenly seemed to use little oil at all!
Of course during the high consumption period we complained like hell and my wife being the rottweiler she is, even found a contact in Italy who pacified us by supplying a paid short holiday!

Weird, maybe the rings didn't set from factory right away?
 
Older German cars used chrome rings, never seated well at all, used a consistent amount of oil. Was strange to remove a cylinder head at over 100k and see hone marks in the cylinders.

Most if not all of the newer engines have used a bit more oil right at first, but 10k seems like a long time.
 
Well, so much to say, hard to know what to emphasize......there are hobbyists who pay for their own oil lab tests so you would only find that type of information in a forum or blog.

About time somebody said something useful: test your oil and see how it is holding up after X months or Y miles. Not a lot of money. Fleet operators do that routinely and may clarify that oil is good for a long time.

I remember like it was yesterday when synth oil arrived (late 80's??). My 1961 BMW motorcycle was started with a kick. Seemed a natural enough way to start a 650 cc 11:1 engine, eh. Like night versus day, the ease of cranking with synth oil, viscosity equal to dino oil.

One major issue not mentioned here is how often you start your engine. An advantage of synth is that it sticks to the cylinder walls better for longer.

Seems to me that "manufacturers recommendations" are often there for CYA legal trickery to protect the manufacturer or to boost dealer service profits.

About colour, with a sight glass on my 1999 BMW motorcycle sump, I can see the colour of the oil. Goes from clear to pretty tinted in a day. So that's no guide. Smell is a good guide DAMHIK.

B.
 
Last edited:
I change my oil and filter every 5000kms no matter what anyone says. It's a cheap routine maintenance and I do it myself. I just use conventional motor oil and buy it on sale so it's not a big deal, and if I can keep my oil as clean as possible I think that is a good thing for all the metal parts involved. If I had a dealer or mechanic say no your car is good for 7000-10000kms between changes I don't care, I'll do it every 5000KMs as I have my whole life with every vehicle I've owned regardless.
 
The first number in the SAE oil viscosity with the W suffix is only relevant to winter operation as this viscosity is measured at an oil temperature of 0C (32F) and represents the oils viscosity in winter starting operation. The second number is relevant to warmed up operation where the viscosity is measured at 100C (212F). Equally important is the API service rating which is a two letter code which started at SA about 100 years ago and advanced through SB, SC etc. and now is at SN-Plus introduced a bit over a year ago.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.