Urban Legend from decades ago ... synthetic oil was "too slick" for engines

[Mechanician]

They guy is clueless. VW doesn’t use a special break-in oil, what was in the engine was the same approval as what was in the owner’s manual. And at that time it was a synthetic 502 00 approved oil.

The whole story seems more like a backhanded approach to prove something else. And not a very good one at that.

Yeah he was trying to impress me with stuff he probably made up. Or heard at work / VOA.
He should have checked here to learn what oil is really used at the factory.
He retired a couple of years later, may have been some early dementia.
If that story attempted to prove something to the all knowing - my apologies.

 

[TomYoung]

Don't forget, the other thing that mechanics were saying at the time was that synthetic oil would cause your car to leak/use oil.
Of course, at the time I think Mobil1 was a 5W-20 or something, nothing thicker in the beginning.
All of it urban legend of course. I switched to synthetic as soon as it became commonplace.

I think we all switched, but may have widely different perceptions of when it became commonplace. I would say that it was somewhere around 1995, but note that Honda was still recommending blends ten years later. I would say Mobil 1 had one or two decades of being a very premium, out-of-reach, too expensive for your Chevy sedan times. That long period probably allowed a good number of the wack myths restated here to develop.

 

[TomYoung]

They guy is clueless. VW doesn’t use a special break-in oil, what was in the engine was the same approval as what was in the owner’s manual. And at that time it was a synthetic 502 00 approved oil.

The whole story seems more like a backhanded approach to prove something else. And not a very good one at that.

Dude has to work on his backhanded redirect approach.

 

[Mechanician]

That owner should have been using a VW 502 00 approved oil, right? I wonder how many fully conventional oils there were that obtained that approval back then?

Why the VW dealer would have used a "dino API rated oil" is a bit of a mystery.

I managed to find a 2002 owners manual online for a Passat - the oil section is a bit different from what you recall. And it actually uses the word Specifications. Apparently an API rating of SH was proper quality, either in petroleum- or synthetic-based oil.

 

[kschachn]

ILSAC GF3 5W-40 was a synthetic oil back in that day.

It still doesn't make that whole "synthetic is too slippery and won't let the rings break in" scenario true. It's still an urban legend.

 

[Mechanician]

ILSAC GF3 5W-40 was a synthetic oil back in that day.

It still doesn't make that whole "synthetic is too slippery and won't let the rings break in" scenario true. It's still an urban legend.

Apparently you missed the whole point of my original reply, to RDY4war's posts about how little mechanics know.

 

[kschachn]

Apparently you missed the whole point of my original reply, to RDY4war's posts about how little mechanics know.

Apparently I did.

 

[Kira]

Does anybody know why something is called an "urban legend"?
Didn't rural locations have to listen to the same stuff?
Why not just legend, myth, fabrication or mistaken notion?

 

[JohnnyG]

Does anybody know why something is called an "urban legend"?
Didn't rural locations have to listen to the same stuff?
Why not just legend, myth, fabrication or mistaken notion?

Because more people were urban at the time.
Or is that a suburban legend?
Sorry GM.

 

[Mechanician]

ILSAC GF3 5W-40 was a synthetic oil back in that day.

It still doesn't make that whole "synthetic is too slippery and won't let the rings break in" scenario true. It's still an urban legend.

Do you think this is pure marketing?
Maybe that old factory rep went to work for these folks after he retired.

"Break-in oil is different from regular motor oil because, by design, it is supposed to allow the rings to wear down the peaks on the cylinder wall to form a good seal. Regular motor oil, in contrast, is designed to prevent wear."

https://blog.amsoil.com/why-you-should-be-wary-about-using-break-in-oil-in-powersports-equipment/

"

 

[tolian21]

I think its not completely Urban Legend, it used to be true long time ago in 70-80s until improvements in additive packs.

There is still some truth when high milage cars that used to run on conventional oil are switched to synthetic all of a sudden start leaking oil. It happened to my dad, he then went back to conventional and leak has slowed down

 

[Glenda W.]

Corvette break in oil.

 

[Aston4]

Mobil 1, particularly in the tri-syn era, contained both esters and AN's, both of which clean. This was also during an era when the performance standards for engine oils were much lower than they are now.

So, if you had an engine that was run on the conventional swill of the era, it likely contained considerable deposits, which also worked as dams that blocked leaks. Switching to an oil with a base oil blend that dissolved these deposits would very quickly reveal these leaks. This is why just replacing the seal/gasket would resolve the issue and it wouldn't come back, because the issue wasn't in fact caused by the oil, simply revealed by it.

That was the theory being tossed around (oil leak blocking sludge/deposits, being dissolved) then. I heard that on both the east and west coasts, and since 100% of normal people were not on the internet then, maybe there was some truth to it. But I personally have never seen any *definitive* proof of that being the *actual* cause of the leaking seals. Maybe it was, maybe it wasn't. But Mobil1 causing leaks, almost immediately, was a real phenomenon in the mid-late 80s.

 

[tolian21]

That was the theory being tossed around (oil leak blocking sludge/deposits, being dissolved) then. I heard that on both the east and west coasts, and since 100% of normal people were not on the internet then, maybe there was some truth to it. But I personally have never seen any *definitive* proof of that being the *actual* cause of the leaking seals. Maybe it was, maybe it wasn't. But Mobil1 causing leaks, almost immediately, was a real phenomenon in the mid-late 80s.

Yes, its not the actual cause of the leak, but does it matter? Car is now leaking oil and before it was not, it does not make people feel better about the reason for it, they now have issue to deal with…
I have seen old car starting to leak oil on synthetic and then leak slowing down going back to conventional. Yes, I know the seals are bad, but still

 

[Hohn]

And he is more likely than an engineer to have changed his own oil?

Really?

Engineers come in two kinds, based on my professional experience. The first knows the book answers top to bottom, knows the theory, and analysis and research. But he or she doesn’t DIY anything, and follows the book strictly.

The second also went to school and knows much of the book answers, but takes experience and empirical data far more seriously than theory. He’s repowered half a dozen machines in his spare time, considers the owner’s manual a starting point, and realizes there’s an exception to every rule. While he’s very curious, he accepts that he might not get to understand “why” and accepts that something just “is” even if the reason isn’t perfectly understood.

 

[ka9mnx]

Back in the 60's my best friend used SAE 30 non-detergent oil to break in his freshly rebuilt Corvair engine. I thought he was nuts but he was probably right.

When I rebuilt my 58 Ford inline six engine, I used Mobil1 5w-20 synthetic for break in. Never had any issues and the engine ran great.

 

[OVERKILL]

That was the theory being tossed around (oil leak blocking sludge/deposits, being dissolved) then. I heard that on both the east and west coasts, and since 100% of normal people were not on the internet then, maybe there was some truth to it. But I personally have never seen any *definitive* proof of that being the *actual* cause of the leaking seals. Maybe it was, maybe it wasn't. But Mobil1 causing leaks, almost immediately, was a real phenomenon in the mid-late 80s.

Well, we have two definitive facts to work with here:
1. Oils of that era were not very high quality and left deposits in the form of varnish and sludge.
2. AN's and esters are cleaners, and used for that purpose.

When I bought my '87 GT T-Top and switched it to Mobil 1, both valve covers started leaking not all that long after, maybe 6 months to a year? This was the early 2000's (and it was a few years later that Tri-Syn was replaced by SuperSyn). Removed both valve covers, which had cork gaskets. The cork was rock hard but otherwise undamaged, which wasn't surprising for 14-15 year old gaskets, but what jumped out was that the surfaces of the heads were spotless. Now, I had no reason to remove the valve covers prior, so I don't know what they looked like on whatever the previous owner had been feeding it, but I think we've all seen what engines run on 70's, 80's and 90's conventional oil generally looked like inside.

But there was nothing done to the cork that "made" it leak. There was absolutely no sign of any damage. The area where it was seeping from had been compressed by the valve cover and, over time, due to the heat, eventually became non-pliable; hard as a rock and unable to maintain a seal between the head and valve cover. So, why wasn't it leaking? I'm going to assume deposits. And when those deposits were eliminated, the leaks were revealed. Fresh valve cover gaskets and the leaks were gone, never to return.

Now, with butyl rubber valve cover gaskets, we see the same behaviour in terms of hardening, but they leak, because of course modern oils are significantly better at preventing deposits than those from decades past.

 

[Mechanician]

Isn't the name "synthetic" too vague to use with such a broad brush stroke?

It seems there are too many properties that vary greatly from one formula to another, to make an accurate statement about how a "synthetic" will affect all engines, in all states of service.

 

[OVERKILL]

Isn't the name "synthetic" too vague to use with such a broad brush stroke?

It seems there are too many properties that vary greatly from one formula to another, to make an accurate statement about how a "synthetic" will affect all engines, in all states of service.

I think in the context of this discussion, we are really only talking about Mobil 1 and AMSOIL, which were the only two "big names" around at the time that these urban legends grew legs.

 

[Hohn]

I think in the context of this discussion, we are really only talking about Mobil 1 and AMSOIL, which were the only two "big names" around at the time that these urban legends grew legs.

Indeed, and since m1 was originally pao based and Amsoil was ester-based, it may come down to whether not swelling enough or excessive swelling was a primary contributor.

Either way, modern elastomers are marvelous and make a truly leak-free engine possible, if the oem would prioritize that and use $$ gaskets instead of “gudnuff fer warrintee.”