2 Engines, each with 500k miles. Difference? The oil: one synthetic, one conventional

[The Sigma]

Ever since laying hands on my Gladiator I have changed my own oil and have always used AMSOil 0W20 because I believe it to be the best of the synthetics for the longevity of my engine. Is it? That's debatable. Is synthetic better than conventional oil? There are a gazillion opinions out there ranging from "absolutely" to "it makes no difference as long as you change regularly". I came across this video, it is the most objective one I've seen and virtually eliminates all variables... as well as the "opinion" factor out of the equation.

Heads-up, it leans very heavily towards the benefit of synthetic.

Sharing it with you fine folks.

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[Lost1wing]

I can definitely see the difference in synthetic and conventional oils. One thing I have noticed on one of my Ford 4.6l engines with synthetic oil, is that is survived a complete loss of coolant for over 10 minutes without locking up. Darned teenagers. I know of other owners that just overheat and lock up a 4.6l. I know they have used conventional oil because that is what the maintenance department uses. It is hard to compare because of the abuse the .gov fleet vehicles get.

Most people really don't care what they put in their vehicles, because they know it's going to be a trade-in in a few years.

 

[Sandman 4x4]

Yea I’ve been a believer in full synthetic oil since Mobil 1 was released. I have tried Amsoil once with the proper weight and factory recommended code, but the very nigh after I spun a rod bearing in my wife’s 1988 Kawasaki Eliminator 250, a water cooled DOHC, 4 valve twin, that had a 14,000 rpm redline, that I never went near, with 75mph turning 7,000 rpm! Never used that stuff again though after that. No, it’s been Mobil 1, Penzoil Full Synthetic, Castrol Full Synthetic. Back in my 2 stroke trail bike era, back in early 70’s I used Golden Spectro T2, mixed with gas or oil injected, with fantastic engine life. I just had the first Jeep Wave compliment oil change and tire rotation, making sure the dealer used the full synthetic oil that happens to use only MOPAR oil. I had the oil changed at 4,500 miles, the new will be 10,000 miles and every 5,000-6,000 after that.

 

[ZeeJay]

Yes synthetic oil is better than conventional, and there are reasons why besides the internet said so. With that said nothing is objective about that test and it sure as hell didn’t eliminate the biggest variable of the test. 10K intervals on two different types of oil, and one has the advantage of resisting heat, viscosity loss, and TBN drift over the other. Asking one oil to do what the other is capable of while itself not being capable of it isn’t objective.

 

[Greg_L]

Ever since flat tappet cams went away in production engines, we don't really need conventional oil anymore. We don't need the zinc and other additives that made conventional oil so good for what it did. Youtube vids and internet opinions don't matter - conventional oil was amazing for it's day and the engine's of it's day. Do we need it now? Nah. Not because the oil is the problem, but because engines are the problem.

 

[BourbonRunner]

I can't think of the last car I had that used real dino juice.

I had a friend way back when that was an Amsoil distributor. He did it so we could get it at/near cost. I ran it in my VW 1.8T and noticed a substantial difference in the valve train clatter. Same for a friend in his e36 M3.

I sent a sample to Blackstone at 5k and again at 10K the first time I used it and there was negligible difference chemically from new. I changed every 10k and sent samples out regularly with nominal degradation over that period.

In my current e46 M54 engine I run BMW-spec Liqui Moly and only that along with their various engine treatments and have every change at 5k with a sample tested by Blackstone. At 144K miles there is no metal and again, negligible chemical degradation to the oil but given that motor can and will go 200K+ with 5k intervals.

For what it's worth, frequent changes with a good quality synthetic, be it Liqui Moly, Mobil 1, Amsoil, Royal Purple, etc is cheap insurance for your motor. And get your oil tested regularly.

 

[ZeeJay]

Ever since flat tappet cams went away in production engines, we don't really need conventional oil anymore. We don't need the zinc and other additives that made conventional oil so good for what it did. Youtube vids and internet opinions don't matter - conventional oil was amazing for it's day and the engine's of it's day. Do we need it now? Nah. Not because the oil is the problem, but because engines are the problem.

That’s the truth there, it’s a moot issue. Engines are a helluva lot tighter than 30 plus years ago more moving timing parts internally and oil factored in as an emissions strategy now. Anything back to mid 90s it’s whatever you want kinda thing. I run old school 10/40 in my two ZJs mainly because all my bikes and ATVs use it so 10/40 is a one stop shop for oil, and even if I did run synthetic it would still drop at 3K regardless because a 4.0 and 5.9 are not clean engines anyway.

 

[BourbonRunner]

it would still drop at 3K regardless because a 4.0 and 5.9 are not clean engines anyway.

Wait, you have a version of God's Own Straight 6 that has enough oil in it to change? I thought you just topped it off and every few months spin a new filter on!

 

[ZeeJay]

Wait, you have a version of God's Own Straight 6 that has enough oil in it to change? I thought you just topped it off and every few months spin a new filter on!

I rebuilt it complete around ‘20 into ‘21. Every mating surface is backed up with grey rtv, although like the model of failure dependability the rear main is leaking(go figure). It keeps all of it now.

 

[BourbonRunner]

I rebuilt it complete around ‘20 into ‘21. Every mating surface is backed up with grey rtv, although like the model of failure dependability the rear main is leaking(go figure). It keeps all of it now.

Nice- those motors will run forever, provided it still has oil in it. A friend had an XJ with one that we road tripped in regularly. Always had 2 quarts at the beginning of every trip. Never had that much when we got back!

But really it must be something about straight sixes, because the 4.0 is like any BMW straight 6- you know it's out of oil when it stops dripping.

 

[ZeeJay]

Nice- those motors will run forever, provided it still has oil in it. A friend had an XJ with one that we road tripped in regularly. Always had 2 quarts at the beginning of every trip. Never had that much when we got back!

But really it must be something about straight sixes, because the 4.0 is like any BMW straight 6- you know it's out of oil when it stops dripping.

25 years around a lot of 4.0s….Renix, HO, Powertech…..massive overheats, low oil pressure, failed lifters, broken pistons skirts, polished cylinder walls. Some of instances didn’t run a few hundred miles more but 50 thousand more…..I will have at least one around until I die. Another one nobody talks about is the Ford 300 straight six, gutless but holy shit is it stout.

 

[BourbonRunner]

25 years around a lot of 4.0s….Renix, HO, Powertech…..massive overheats, low oil pressure, failed lifters, broken pistons skirts, polished cylinder walls. Some of instances didn’t run a few hundred miles more but 50 thousand more…..I will have at least one around until I die.

You're doing God's work.

 

[Killroy Was Here]

Since all 0W-20 oil is synthetic, afraid I don't understand what the comparison of synthetic vs. conventional oil has to do with the Gladiator?

 

[JTenn]

On the topic of oils, my 24 Ram has the 6.7 Cummins. I was surprised to see Cummins recommend oil is 10W30 at 15000 mile interval!! Nope!! No way I can run oil that long in any engine. But that seems pretty thin weight for a diesel engine. I will admit I'm fairly new to diesels but I had a 6.0 Power Stroke before this one. I always ran conventional Rotella 15W40 in that engine and changed every 5000 miles. All 16 quarts of it, lol. At least the Cummins only takes 12........I think

 

[ZeeJay]

On the topic of oils, my 24 Ram has the 6.7 Cummins. I was surprised to see Cummins recommend oil is 10W30 at 15000 mile interval!! Nope!! No way I can run oil that long in any engine. But that seems pretty thin weight for a diesel engine. I will admit I'm fairly new to diesels but I had a 6.0 Power Stroke before this one. I always ran conventional Rotella 15W40 in that engine and changed every 5000 miles. All 16 quarts of it, lol. At least the Cummins only takes 12........I think

Your safe man, let’s just say I really really know that product, like I’m in the food chain somewhere with that product. Only thing I’d change is OCI’s @ 10 and not 15. I ran a 2011 Kenworth T370 with a 300 horse B and fed it 10/30 for most of its life. 26,000 pound truck that did more work in a week than nearly all Dodge pickups do in a lifetime. I’m running it now it the replacement 2023 Frieghtliner M2-106 with a 260 horse B. I’ve put 8000 miles on it since September 17 when I came back from short term. There is a reason 10/30 is spec for that engine.

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