Most Economical Type of Engine Oil?

baskinghobo on 31/01/2021 - 01:27
Last edited 02/02/2021 - 11:50 by 1 other user

I read that the type of engine oil doesn't really matter for most people unless they have a high performance vehicle so is there any reason why a regular person should buy full synthetic engine oil over mineral oil? Does it protect against engine wear better?

The reason I ask is because I had a service with an oil change about 6 months ago and am due for a new one according to the mechanic but I read on the manufacturer booklet that my Mitsubishi Lancer 2008 only needs to be serviced every year/15,000km and I also read on here that oil changes don't really need to be done every 6 months so I am going to wait another 6 more months and do the oil change with the service. I am not sure what type of oil the mechanic put in last, it just says 5w-30 engine oil on the receipt. It's already passed 6 months/5000km since he last put it in. If it is mineral oil would I be ok to wait another 6 months or should I get another oil change done just in case? I heard synthetic oil lasts longer but surely mineral oil can last longer than 6 months/5000km?

Automotive Engine Oil

Comments

zonra on 31/01/2021 - 02:33

+3

Most economical = cheapest you can get your hands on I guess?
Too many specific questions in your post so I’ll just try to offer some general ideas:

Full synth should last longer than mineral.
Considering full-synth oils often go on sale for ~$30 per 5L (enough for 1 oil change), I can’t see why one wouldn’t go for full-synth.
The car is unlikely to explode if you miss a service, I’ve seen Corollas that run for 100k+ without an oil change (delivery vehicle where business owner doesn’t care). The damage will be there but how severe will depends on a lot of things (engine existing condition, driving habit etc.)
Unless you change the oil yourself, I wouldn’t trust your mechanics to put in full-synth even if you requested/paid for full-synth.
Make sure you get the right viscosity if DIY, use manufacturer websites to check compatibility.
- baskinghobo on 31/01/2021 - 10:06
  
  Thanks but why wouldn't you trust the mechanic to put in the full synth if I supplied it because that's what I was planning to do.
[Deactivated] on 31/01/2021 - 04:21

+10

80% of engine wear occurs during start-up and the approximately 10-15 minutes duration it takes of regular driving for the car to reach "optimal temperature" where the oil works its magic.

The other 20% is through driving itself including idling in traffic , stop-go and random start/stops.

Engine Oils are classified into 3 main types

*Mineral
*Semi-Synthetic
*Full Synthetic

However due to the the fact there is no regulation in the oil industry at least in Australia , you can pick a bottle off the shelf that states it is a full synthetic but the composition of the oil itself is that it is a Synthetic BLEND rather then a True Full Synthetic. You will never know the actual % of synthetic stocks in an engine oil as the manufacturers keep it secret so they can keep their monopoly going.

Watch THIS first to get a base understanding of the difference in FLOW , i skipped to the juicy bit but feel free to watch from the top.

So if 80% of engine wear occurs at the start and within the first 10-15 minutes of driving until it warms up , the most IMPORTANT aspect of engine protection is getting an oil to pump through the motor and oil gallieries as fast as possible so the metal parts can be protected by the oil.

So in terms of flow speed , slowest to fastest based on composition it is Mineral > Semi-Synth > Full Synth , but oil weights actually make a difference here too so that has to be taken into account. see HERE for oil weight explanation.

So the most ECONOMICAL oil you can use is one that is light enough that your engine can handle from factory based on its current conditions , the lighter the oil weight the faster it flows the less energy your engine has to use to circulate the oil around the less petrol it uses and the better it responds. it is as simple as that , but you should ALWAYS follow your manufacturer approved oil recommendations from your manual. The only time you should deviate is if you live in a hotter/colder climate or you have an engine that is aged and needs a thicker oil as preventative maintenance or if you take your car to the race-track.

Engine oil needs to be changed every 1 year or a set amount of distance travelled , whichever comes first. it greatly depends on the manufacturer , some will specify 15,000km others will specify 20,000km. the reality is even if you have not travelled that duration you should still change it on a yearly base , because what people don't know is oil actually gets THICKER over time as it loses its additive properties and collects dirt/debris that the oil filter has not been able to filter out and collect. when oil gets too thick it will eventually leak past rubber seals and cause oil leaks , if the oil is not changed and it is still left to try and circulate through the engine (if it can) it will look something like this once it is pulled apart after it breaks which can be extremely costly , if you want to see HOW a sludged up engine is restored see HERE and just bare in mind how LONG it would actually take just to clean the motor and not to put it back together and get it fully operable as well.

Anyone who owns a performance vehicle with either a Turbo or Supercharger and wants reliability from their car should ideally fill up their engine with Full Synthetic and change every 5000-10,000km only if it is feasible for yourself to do so , as any car that constantly gets stuck in any stop-go traffic is falls under a "severe service" category and performance vehicles have a lot of force and heat they have to contend with from our driving that is the complete polar opposite to what a standard commuter car faces.

Semi-Synthetic and Full Synthetic oils tend to fare better in terms of both time and duration of km's travelled on them as they take longer to degrade compared to mineral.

@OP/baskinghobo , based on your comment i would say it is safe to leave the oil you have in there for another 6 months/5000km , the oil weight you have in the car is a standard weight that is neither too thin or too thick on your application based on your car model and how long the oil has been in there already.

For a standard A-B or commuter car , a semi-synthetic is recommended but the reality is a mineral is perfectly fine as long as it is changed on schedule.

Anyone reading this thread , if you think you are due for an engine oil change. do it and don't second guess yourself , don't be that person that breaks down in the middle of the road not only putting yourself and others in danger but causing a massive inconvenience for everyone around you and diverting roadside assistance attention to yourself rather then people who really need it.

I know this is Ozbargain but don't be that person that quibbles over something as important as a car service. for the sake of $100-150 it is worth the peace of mind.
- baskinghobo on 31/01/2021 - 12:26
  
  Hmm maybe I should do a oil change just in case then because my manufacturer's booklet says I should change the oil every 5k but I highly doubt mineral oil suddenly stops being effective after 5k.
  
  This is the comment that made me think oil changes don't need to be done so frequently - https://www.ozbargain.com.au/node/106988#comment-1451748 . Although he does mention to use full synth which I don't know if I'm using. Also I'm aware most synthetic oil isn't true synthetic (group 4 and ,5) but the fake synthetic like the Castrol edge 5w-30 can't be that much worse and based on the comment I'd say it's rather safe to perform an oil change once a year if you're using full synth but then again I'm not a mechanic.
  - [Deactivated] on 01/02/2021 - 15:06
    
    +1
    
    if your car is literally a stop-go city car or you are in stop-go traffic alot , like walking pace. engine oil heats up constantly and does not get as much time to cool down by recirculating through the engine via normal driving therefor the engine oil breaks down faster , also the thicker the oil the more heat buildup because it does not flow as fast through the engine that is constantly in stop-go.
    
    most jap cars are well built and can easily go for a more prolonged oil change interval mostly due to improvements in oil technology over the last few decades paired with the tighter tolerances in engine design.
    
    as mentioned previously , for most A to B cars a semi-synthetic is realistically all you need but if your wallet is saying mineral then that is fine too , the most important aspect is just changing it regularly.
    
    additionally engine oil tends to be less contaminated with the use of premium fuels (95+ and higher) , i have a car in the family that was using 95 octane for years and full synthetic oil , 10,000km's after the oil change the oil still looked almost as good as the day i put it in which led me to believe i could have easily got another 10,000km's out of it. but i chose 10k intervals as a nice sweet spot.
    
    i on-sold that same car to a family member who decided to only put 91 in the car and i checked the oil at around 8,000km's and it was pretty dirty which led me to believe that the fuel you use also makes a difference to engine oil longevity as in my particular case everytime without fail when i service a car a brand new oil filter is put in.
    
    anyway food for thought , but the main takeaway here is take care of your car and it will take care of you.
    
    @baskinghobo there is no harm changing it for that peace of mind if you like , also castrol edge titanium is made from group 4 base stocks so it is closer to a true synthetic compared to the magnatec and most jugs claiming to be full synthetic ( i.e nulon next / castrol magnatec / and penrite 5w-30 (with the exception of enviro+) , just to name a few off the top of my head.
- FlipCrank on 31/01/2021 - 14:41
  
  -1
  
  Do you have a source for that 80% wear figure. Honestly sounds like a bunch of malarkey.
- muckingfuppet on 01/02/2021 - 10:29
  
  THIS. The true bargain is not having to repair your car because you put donkey's piss instead of oil in your car.
dmbminaret on 31/01/2021 - 06:56

+3

I change my own and just buy the one that is recommended for my vehicle on supercheap's site when it is 40-50% off.

Ryco filter from them too or sparesbox on ebay when ebay plus have 20% off.
pharkurnell on 31/01/2021 - 11:05

+2

There are some things in life you can skimp on..
but IMWO Look after your car and it'll look after you.
[Deactivated] on 31/01/2021 - 13:28

+1

It would likely be a semi synthetic as there are no 5W30 minerals (that I know of). It should be fine to do 10,000km given your current 5000km/6month situation. I wouldn’t push it to 15000km if I were you. And brands can make a difference too.
I have a 2009 CJ 2.0 lancer and have tried a few full synthetics. Most of the time I put in 4.5L and after 6 months get 4-4.2L out, except for when I used Castell magnatec 5W30 FS. After 6 month it degrades that much only 3L came out.the last 2 times using nylon FS it has gone back to 4.2 and 4.3 litre drains.
In summary, castrol = rubbish.
- mapax on 31/01/2021 - 14:34
  
  except for when I used Castell magnatec 5W30 FS
  
  Well there’s your problem, it sounds like you’ve gone and purchased a knock-off…
  - [Deactivated] on 31/01/2021 - 15:26
    
    Damned auto correct. My summation was for castrol though.
the Unforgiven on 31/01/2021 - 15:55

Don't worry about changing your oil every 6 months, it is just not worth it with modern engine oils; just change your engine oil every 10,000kms, along with your oil filter. To find your cars engine oil, use a cars website like SuperCheapAuto.com, just put in your rego & you get a range of oils to choose. Do not choose cheap oil from the supermarket, if you love your car, look after your motor; use a known brand.
brad1-8tsi on 31/01/2021 - 16:15

+2

Did you read the severe service criteria?

Among other things if you do lots of short trips or drive in heavy traffic the oil should be changed more often. Is this part of your driving conditions?

Cut back on maintenance now and you'll know about it in a few years time.
Silver-Arrowz on 31/01/2021 - 17:27

+1

If you care about your car then the question is "What oil specifications does my engine require?"

If you don't care about your car the question is "What's on special?"

If you want an in-depth answer then this channel Engineering Explained is good.

What if you forget to change your oil?
https://www.youtube.com/watch?v=eVyPWP5t09c&ab_channel=Engin…

Is Synthetic Motor Oil Bad For Old Cars?
https://www.youtube.com/watch?v=pPFSR-2lhxY&ab_channel=Engin…

Is Synthetic Motor Oil Better For Your Car?
https://www.youtube.com/watch?v=tYkg0oDUXs8&ab_channel=Engin…

Motor Oil Myths & FAQs - Synthetic vs Conventional
https://www.youtube.com/watch?v=Se8-W7rK0H4&ab_channel=Engin…
Euphemistic on 01/02/2021 - 15:26

How many kms on the car and how many more do you want/need to put on it?

The less life left in it, the less you need to pay for oil. If it’s only got another 2-3years why it for premium oil for negligible benefit, unless you are doing a lot of hard/harsh condition driving and need something ultra reliable.

If on the other hand you want to hold out for another 10 years while you save for an electric car then service and maintain it the best you can. Including better quality oil.

Most Economical Type of Engine Oil?

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