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Mineral oil is better than synthetic oil for older engines?


Gaurav

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After my recent Pajero engine failure, I'm doubting everything to anything that comes across relating to engine maintenance and health. I have been using a semi-synthetic blend of Mobil1 - 10W40 always. As per my Pajero owner manual also says 10W40. Mobil1 - 10W40 has a life of 7k kms, and I always change between 4-5k due to offroad use. And when the engine failed that oil was less than 2k driven, and upon inspection as per mechanic educated guess - oil must have thinned out too much under stress and fail to reach to all parts and shot the engine or oil pump failed partially. 

Now some advices that using mineral is better than synthetic as it will not become thin under stress like water and help provide all-round lubrication under stress too. Is it true.....?

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No it's not, as stated previously in this thread, semi synth is bogus as even 1% synth oil mixed in and it can be called semi synth as there is no set standard as what qualifies as semi synth. 

Also as mentioned earlier and many disagreed to this but 40w is too light for this country where temps in summer are always above 40 more close to 50. 

I've read many owners manuals that say to use higher grade oil in higher temp environment, Ive posted a chart from my own manual sonewhere in this forum showing the same.

Using fully synth 50w oil and you should be fine. You can switch back to 40w in cooler months if you like

 

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13 hours ago, shadow79 said:

in older engines there is more clarence in between the parts so better use the thicker oil which when heated will change less in viscosity 

Not that it matters because Gaurav's engine is already scrap, but I don't think oil viscosity was the primary reason the engine failed. Think about it- there are hundreds of thousands of vehicles all over the Middle East running on oil  formulations similar to Mobil1, and yet their engines don't just blow up without warning. 

I'm inclined to think that this engine had been running with bigger than normal clearances on the crank, and/or cams, and/or oil pump for a long time, and the engine failed when the combination of large clearances and thin oil reached a critical point, i.e., when the pump could no longer maintain oil pressure with the thin oil escaping from overly large clearances. 

However, as @desertdudesaid, changing over to a heavier oil viscosity might prevent a repeat of the problem in the replacement engine, but also as he said, make sure the oil is a pure synthetic- no blends or semi-synthetic formulations.    

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Thanks @desertdude, I rem that semi-synth explanation, which does make sense and will be sticking to full-synth or mineral now - if everyone thinks it's better over fully-synth in an older engine.

@shadow79, if we go by your pointer on more clearance need thicker oil, then what happen if engine spec need synth and semi-synth from owner manual and you feed with mineral, which will result in uneven lubrication - as per previously explaining thread that talks about the major difference between Synth and Mineral is the consistent lubrication. As synth has regular molecules compare to mineral oil - uneven molecules.

@treks do you also think that in an older engine, thicker viscosity blend is better than thinner.....?

Another observation: Since last 7 years I'm using Mobil1 purchased from Dubai authorized dealer, but since 3-4 months I have sourced a tad cheaper Mobil1 from Ajman, as a clearance of old stock. Is that older stock could be a concern to get the oil to such a thinner level.......?

I personally feel it may be something else, as I have been pushing this car lot more for continuous hours and hours and it never died like this. On the contrary, the day when an engine died, we had a very relaxed drive in the night and took a break for 2 hours and I checked the engine oil level too and color too while passing time. After that, we had 5 km track and tarmac drive before hitting the hill climb challenge means the engine was super relaxed and in an ideal operating temperature. Within the second or third climb attempt engine made those nasty rockers noise and I exited.

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there are engine with different specs of oil i agree but what about you starting in the morning and its running dry for a sec or 2 everyday...it does affect its clarence levels that after a good amount of time they are making sounds so hence to prolong that last bit of usable life you can toss in mineral oil in it

and before the trump of these synthetic oils there were 8 cyls and 10 cyls and 12 cyls and 16 and 32 cylinders what were those running on and on top of that there were competitions too it was the mineral oils which were running in them....

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Why use old technology when you can use new? It’s like having a car with points that need to be adjusted every couple of months when you can replace it with an electronic unit and be done with it. Upwards and forwards.

Modern synthetics come with additives that help adhesion to moving parts after switch off so that first couple of seconds where the oil is pumping up to the head isn’t so much of an issue nowadays. Even years ago people were using additives from companies like Slick 50 and Molyslip to combat this. 

Also, I think if an engine has started knocking, it’s a waste of time trying to use thicker oil, the damage has already been done. A set of bearings is the price of a few gallons of good quality oil and in a lot of cases they can be changed in a couple of hours just dropping the sump off for access. 

Once the clearances have increased, the oil pressure drops. When the oil pressure drops, protection drops, parts wear more, pressure drops, parts wear more and it continues in a vicious circle until the point of catastrophic failure. 

I myself had an old car that would sometimes drop to 3-4 psi because of a crankshaft problem. I used to mix a pint of 80w90 in the engine oil just to keep the engine running. I was planning to fit a bigger engine so I didn’t care what happened the old one. It eventually snapped the crankshaft. I wouldn’t do this on anyone else’s car but it’s an example of how using thicker oil instead of fixing the problem can go wrong. A lot of the time it’s just masking the noise, a bit like adding sawdust to an old differential, but the problem is still there. 

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1 hour ago, Gaurav said:

Thanks @desertdude, I rem that semi-synth explanation, which does make sense and will be sticking to full-synth or mineral now - if everyone thinks it's better over fully-synth in an older engine.

@shadow79, if we go by your pointer on more clearance need thicker oil, then what happen if engine spec need synth and semi-synth from owner manual and you feed with mineral, which will result in uneven lubrication - as per previously explaining thread that talks about the major difference between Synth and Mineral is the consistent lubrication. As synth has regular molecules compare to mineral oil - uneven molecules.

@treks do you also think that in an older engine, thicker viscosity blend is better than thinner.....?

Another observation: Since last 7 years I'm using Mobil1 purchased from Dubai authorized dealer, but since 3-4 months I have sourced a tad cheaper Mobil1 from Ajman, as a clearance of old stock. Is that older stock could be a concern to get the oil to such a thinner level.......?

I personally feel it may be something else, as I have been pushing this car lot more for continuous hours and hours and it never died like this. On the contrary, the day when an engine died, we had a very relaxed drive in the night and took a break for 2 hours and I checked the engine oil level too and color too while passing time. After that, we had 5 km track and tarmac drive before hitting the hill climb challenge means the engine was super relaxed and in an ideal operating temperature. Within the second or third climb attempt engine made those nasty rockers noise and I exited.

The age of the engine is not so important as is its condition with respect to clearances. If you get a new engine with in-spec clearances, using thicker oil might actually be detrimental during cold starts, since the thicker oil is much more difficult to pump around the engine.

In  your case, it is difficult to say what caused the big clearances, but as per your above post, it makes sense the engine would have died while driving slowly- when it was on the verge of failing anyway. 

When you were dune bashing, the engine was running at high speeds, which helped to keep the oil pressure up. When you were driving at lower engine speeds, the lower engine speed could not keep up the oil pressure, causing the loss of lubrication.  

This engine was on the point of blowing up anyway, and it could have happened on your way to the office, or shops, or anywhere- it is just coincidence that it blew up after a dune bashing session.  

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my clearance statement is in regards of the engine as a whole is old technology hance having more clearance and the newer models like 2015 or 2018 engines having very minute clearance in between the rubbing parts (not the damaged clearance which in turn requires repairs)

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  • 1 month later...

Back again now, that I can't find any brand that does fully synthetic and 50 other than this Mobil 1 which is not available in UAE.

Appreciate if someone can help source 0W50 or 5W50 fully synthetic engine oil in UAE, please.

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