Move from synth to dino for aging engine???

[bigjohn]

This is a general question regarding all gas engines, as they age and rings and valves wear and loosen up a bit.

This is not a motorcycle only question, but I have noticed on a couple of my motorcycles, that as they age and the miles pour on them that they are starting to consume a tiny bit more oil over the life of the OCI. On one of my bikes, I have switched to conventional HDEO and the consumption has been drastically reduced.

Years ago, we purchased a Jeep Wrangler for our two boys that had 165k miles on it. We poured in synthetic oil and the engine burned like a smoke wagon. We switched back to dino and the consumption drastically decreased.

Here's the question.... At some point in aged and long wearing engines, is it a good move to switch from synthetic to conventional oil?

Yes, I know that at some point engine work will have to be done, but that's not the question here.



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[jdavis]

I really think it depends on the maintenance and OCI's over the lifetime of the engine..

 

[Rolla07]

How much oil burned when using syn? When switching brands I see some oil gets burned i would have given it a couple oil changes first prior to switching back to conventional.

 

[fdcg27]

I think you've answered your own question.
If an engine seems to have excessive consumption then going to something a little thicker even within the same grade range might solve the problem.
There is no clear dividing line between oils labeled as conventional and those labeled as synthetic. There is instead a wide grey convergence zone.
If a conventional oil solved the excessive consumption problems with the Jeep and with your bike, then you have your answer.
Engines obviously wear and valve guide seals can deteriorate with age. If an engine never exhibits excessive consumption, though, there'd be no reason to make any changes in the oil used.
If consumption does increase to drastic levels, then you've given us a useful reminder of just how simple the fix might be.

 

[FCD]

Switching to a 20w50 conventional ( specced by Ford ) and changing the valve seals in my motor has really reduced my oil consumption A LOT , Less than half of what it used to burn through ( 10w40 syn blend )

 

[bigjohn]

Originally Posted By: fdcg27
I think you've answered your own question.
If an engine seems to have excessive consumption then going to something a little thicker even within the same grade range might solve the problem.
There is no clear dividing line between oils labeled as conventional and those labeled as synthetic. There is instead a wide grey convergence zone.
If a conventional oil solved the excessive consumption problems with the Jeep and with your bike, then you have your answer.
Engines obviously wear and valve guide seals can deteriorate with age. If an engine never exhibits excessive consumption, though, there'd be no reason to make any changes in the oil used.
If consumption does increase to drastic levels, then you've given us a useful reminder of just how simple the fix might be.



Fair enough.....

But I guess I need to deepen my question. Do conventional oils tend to "glaze" engine parts, whereby reducing consumption? Is there some other reason why conventional oil are consumed less? And do great oils like Mobil 1 tend to clean engines up and create more 'seep' between the rings and valve seals?

I do have conclusive proof that synthetics in my motorcycles are consumed faster. (Remember that most motorcycles tend to consume a little oil....just the way it is.)

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[FCD]

Conventional oils and Group 3 synthetics seem to cling better to parts , PAO and Ester based synthetics seem to have less surface tension and drain down quicker

 

[BrocLuno]

+1

Part of this has to do with the nature of the oil chemistry and the inherent surface tension (or lack thereof) of the base oils ...

This is one area where experimenting with syn-blends can be useful. But since I'm a huge advocate of HDEO's, I just go there and skip the experiments with higher mileage motors

 

[rideahorse]

Now you know why I say that syn oil is just marketing hype. If you would have just run HDEO oil since it was new it would not have wore the motor out to where it uses oil. Syn oil is not better. It is more profitable for the oil company's.

 

[jorton]

"Years ago, we purchased a Jeep Wrangler for our two boys that had 165k miles on it. We poured in synthetic oil and the engine burned like a smoke wagon. We switched back to conventional and the consumption drastically decreased."

Obviously some synthetic oils are not compatible with all other types/brands as they claim to be!

If the previous owner had used the same synthetic you poured in, yours would not have burned. Members post pics of varnished engines that were run on conventional oil and others post pics of clean looking engines that were run on synthetic. It sounds like your used Jeep was raised on conventional.

I do not know if an engine that's raised on synthetic lasts longer, but I do not think it has to be switched over to conventional due to high consumption after it has aged.

 

[Nick1994]

I did the opposite, put in synthetic in my old Camry. I only use free/very discounted oil anyways. I don't care that it burns a bunch of oil, I just top it off. Keeps the mosquitos down in the neighborhood.

 

[UNC017]

Originally Posted By: BigJohn

Here's the question.... At some point in aged and long wearing engines, is it a good move to switch from synthetic to conventional oil?

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Not in general. The only real reason to change would be economics- if it starts consuming so much oil that you're wasting money adding synthetic, then I'd drop to a cheaper oil until a rebuild. Otherwise, stick to whatever has been working well. I've had a couple of 200k+ mile engines that did great on synthetic, and no way would I have changed anything at that point.

 

[dwendt44]

Just going up a grade/weight might do as well.
Some brands tend to be at the thin end of a weight, so at the high end (German Castrol).

 

[SwampSurvivor]

Originally Posted By: 440Magnum
Originally Posted By: BigJohn

Here's the question.... At some point in aged and long wearing engines, is it a good move to switch from synthetic to conventional oil?

......


Not in general. The only real reason to change would be economics- if it starts consuming so much oil that you're wasting money adding synthetic, then I'd drop to a cheaper oil until a rebuild. Otherwise, stick to whatever has been working well. I've had a couple of 200k+ mile engines that did great on synthetic, and no way would I have changed anything at that point.



I'm going to hit 206K on my Jeep 4.0 this weekend. 5000 miles on this run of synthetic and only had to add half quart of oil. I'm pretty confident that it doesn't burn any* oil ... it leaks out of the VC gasket and oil filter housing. Which is fine.

*Yes, I'm aware that every engine burns a small amount of oil.

 

[SR5]

Sometimes as my bikes & cars age, I would move up to a heavier synthetic from a lighter synthetic. Mind you, being Aussie, I'm often at the heavy end from day one.

What grade HDEO did you use in your bike ? A 15w40 ? And what was the previous oil ?
Just making sure we are comparing apples with apples, because there is a fair bit of variation within a viscosity grade, and HDEO tend to be at the thick end of the grade.

It's not unusual to have some consumption when changing oil types, but it often settles down.

When I get a new to me second hand car and I don't know the oil history, I tend to start with a semi-synthetic oil on my first oil change, then I go to full synthetic on my second oil change. I've never had above normal consumption problems doing that.

 

[bigjohn]

should I open up the can of worms? ...... should I?

Without exception, Mobil 1 blows by rings and valve seals faster than anything I have used.

I am quickly becoming a conventional oil guy, except in my turbo diesels.....which will get RT6 or appropriate.


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[BrocLuno]

Synthetics have two disadvantages (depending on how you look at it...). They have lower surface tension so they have some drain-off issues and that is not always good for older engines with somewhat worn bearings. They also thin out under pressure, so under heavy loads they can exhibit less viscosity. There are discussions here and there on this site talking about both. Neither is a bad thing in a new tight engine.

But you get an older engine up around 150,000 miles and it'll rattle when you fire it cold, and it will burn through syns more quickly. So some folks switch down to a semi-syn as first step, usually a high mileage oil like Maxlife red bottle. And that may take them far enough to be completely comfortable.

But, since I have a number of vehicles over 200,000 on the original engine and they are expected to carry on for the foreseeable future, I have switched them to conventional oil. I'm quite happy with conventional oils. There are plenty of good ones out there

I do 4~5K oil changes with conventional and it allows me to get a better look at the whole motor/transmission/transfer case, etc. With that many miles, you have to be on the lookout for stuff leaking or going bad...