How long a Fully Synthetic Engine Oil 5w-40 can last?

Well I've certainly forgotten plenty.......

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On the lubricants side, what I know most about are engine lubes for stationary and marine diesels, gas engines, turbines and electrical transformers. But that knowledge is leaking away - or no doubt being overtaken by developments since I retired - too.

I wouldn't mind Timojin too much, were it not for his annoying habit of making shit up and presenting it as fact.

(I may be quite off the mark but I now have a mental image of him: probably Malaysian or Indonesian, raised on a diet of anti-colonial propaganda at the expense of actually bothering to learn science properly, and working in a non-scientific role at a lab in some nationalised industry. I have come across quite a few individuals like that in my career, and he seems to fit the stereotype perfectly.)

 

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<-----------------not a tribological expert.
For engine oil, I go with lubricity----especially in the diesel truck where the oil darkens within days of the oil change.
When checking the oil level, I clean the dipstick with my thumb and a finger, then rub the 2 together to test lubricity-----if the oil still lubricates well, and doesn't smell burnt----------i think it safe to drive on it.
Caveat----oil is cheap, engines ain't. Err on the side of caution.

 

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So you are on the green pastures . The forum is good it keeps us from rusting away , and some challenge should not disturb you but sharpen you.

 

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Haha, you remind me of truck owner-drivers the world over. I recall market research we did in the 1980s that came back with exactly that - thumb and finger test for "lubricity" and a concern about dark oil. There is, not surprisingly, more to it in a scientific sense, but marketing to owner-drivers was always a challenge. I remember we got into trouble in Saudi Arabia with owner-drivers when we upgraded one product and as a result it got lighter in colour. This caused a perception that it was less viscous, even though the viscometry was identical - my solution was to incorporate a bit of a dark dye. (But we HAD to upgrade it, even though the truck drivers hated the change. They would have been happy to buy the old stuff, which was cheaper for us to make, but we knew eventually it would not be good enough for modern truck engines and we would be blamed if there were failures resulting from their choice to use a product that did not meet the latest specs.

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But these guys were traditionalists who bought on brand, not on specs at all. So we ended up giving away the extra performance at the same price, just to keep our consciences and protect the longer term reputation of the brand.)

But changing oil frequently won't do any harm, even if not strictly necessary. Of course doing that makes more profits for "Big Oil" [boo, hiss], so Cosmic won't like it.....

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People can do what they want. I only relay what I've always done. Like I said I also check the undercarriage and rotate the tires when I change the oil. Better to keep an eye on everything with the car because one day something might be wrong and if you let it go you might get even more problems.

 

Who do you think you are?
What chemistry degree qualifies you to do a character profile like this? You twit.
You may know about oil but I would bet you know nothing about being nice. I know several people with degrees who carry on like you. To them life is a one way highway, any diversions from their degree is not relevant and do not have to be entertained. Get a life and remember it cost noting to be nice some of the time.

 

For many years now the advice my part of the world is to NOT regularly rotate the wheels. Since doing so can hide issues with wheel alignment that would otherwise show up.

 

If you read the other contributions by this person you may get some idea about why he irritates me. But whether you do is up to you of course.

 

I think a good full synthetic oil can easily last 10,000 miles; 15 km. The trick is you need to change the oil filter every 5000 miles or 7.5Km. After you change the filter, you recycle the same oil. You top off with fresh oil. The oil will last, but the filter will foul, so the extra filter change keeps the engine cleaner.

I use a semi-synthetic oil, and change oil and filter, every 5000 miles.

 

If you had an alignment problem it would start showing up within 5000 miles so it is better to keep an eye on those tires and by rotating them and balancing them they would be much better off than waiting for over 10,000 miles before looking at them. Catching a balancing problem is easy to do within 5,000 miles. If you see a misalignment you could easily fix that problem before the tires are worn out on one area of the tire or more.

 

changing oil filter will cause oil leaking,
how to change it?

 

It's all relative and maybe in your case regular rotation is the way to go. My old AE71 Corolla s/wagon was very prone to wheel misalignment from even minor potholes or slight bumps with a curb. Whereas an average suburban bound SUV owner probably never need worry about such things, and the huge expense of tyres for SUV's warrants that regular rotation in order to wring out the max tyre mileage possible. As for wheel imbalance, shake/shimmy should make such obvious without ever a need to inspect tyre tread pattern.

 

I do alignment and balancing every 50000 km.

 

There is also 0w-20 oil, will it last even longer?

 

https://www.cars.com/articles/2013/08/expensive-oil-changes-are-here-to-stay/

 

Yes indeed. These lower viscosity oils are designed with fuel economy in in mind. The goal is BOTH to reduce the frictional loss due to viscous drag when the engine is running, AND to enable smaller and lighter starter motors and batteries to be used. (The "W" part of the viscosity classification refers to what is called "cold cranking" viscosity, i.e. when trying to start the engine at low ambient temperature. Clearly the motor and battery need to be sized for the worst case scenario, to ensure you can always start the engine, and the viscosity of the oil when really cold has a big effect.) Motor manufacturers nowadays pay attention to the tiniest detail that can affect economy, on the principle that it all adds up. Lubricant viscosity is one of the factors affected.

As the article implies, if you try to make a 0W-20 with mineral oil, you need very light components which suffer from volatility, leading to thickening in service and oil consumption. Synthetics however can be tailored to give the same viscometrics with fewer of the "light ends" that would get evaporated from an equivalent mineral oil fraction.

So these oils get more expensive. However the flip side of synthetics is long duration so, if you actually follow the handbook, and resist the temptation to change oil early, you may find the cost is not such a big deal.

 

I'll just state one last time it, to me, is more prudent to change the oil with regular oil every 4000 to 5000 miles for you can inspect the undercarriage of your car and rotate and balance the tires as well. Under normal conditions regular oil changed frequently will not lose its viscosity during that time period. My mechanic doesn't charge for the tire rotation because the car is already on the lift so there's nothing that will affect him doing this at this time. You all do what you think is right for your vehicles as at least you are changing the oil and not letting the changing go on and on for far to many miles before you change your oil.

 

Hi I don't mean to have a chip on my shoulders . I tend to disagree that the so called synthetic lubricant have advantage from the description it would be worse If the PAO is based on alpha double bond on the mineral oil, that tells is more susceptible to oxidation , and a loss of carbon. unless the olefin gets to be oxidized and converted to an alcohol or carboxylated group there is no advantage . If the oxidation takes place to carboxylation then the product will add an additional factor to extreme pressure additive I can see the advantage the polyesters brings, wen cleaved they add also the extreme pressure additive , but in these case they have to add more corrosion inhibitor. At the end I am not sure if there is an advantage over mineral oil base if the individual changes oil at the prescribed suggestions.

 

No, you clown. PAO means poly-alpha olefin. The monomer has an α-double bond, from which an oligomer is formed, which is a saturated (branched) hydrocarbon.

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This latest comment of yours demonstrates, beyond any lingering scintilla of doubt, that you have no clue about lubricant chemistry. You are just making up stuff as you go along and pretending you have knowledge of the topic. In other words, you are just talking out of your arse. Again.

And people wonder why I get pissed off!

 

In order to have an lubricant of such range, the lubricant must have a thixotropic agent . and what the thixotropic agent does changes viscosity with temperature and as in this case as temperature increases the so called salting out takes place ( some low grade of separation in the mix takes place )