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

[Aston4]

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.”

Could you please give Toyota a ring and explain this to them? Thanks!

 

[Hohn]

Could you please give Toyota a ring and explain this to them? Thanks!

They already know this. But they aren’t designing something to seal forever, they are designing it to be “good enough.”

 

[JRay’07]

This urban legend doesn’t specify which synthetic base stocks could cause issues. So if you make the transition from group ll+ to group lll your engine will suddenly develop problems? What about the rest of the additive package and the included anti-wear components? There are many other variables to consider.

 

[TheOilWatcher]

Don't forget "Once you use synthetic, you can *NEVER* go to any other oil...EVER!!*

 

[john_pifer]

Let's not forget Dura Lube. The way that stuff was marketed it could fix anything. They practically stopped short of calling if an elixir.

I used all of those back in the day in the ‘90s. Duralube, Slick 50, Prolong, and I think there was one more.

Of course now we know that most are snake oils that dilute the add pack of a good oil, and any immediate benefit (chlorinated parrafins) doesn’t help, and may actually be detrimental, long-term.

 

[Accent Abuser]

Certified mechanics might disagree. Are you an oil engineer? I know an oil company management person who agrees with mechanics.

I know an oil engineer too, but we've never discussed this topic. If I get the chance I'll talk to him about it. However, I don't know how much he knows about cars. The oil engineer I know is part of a team that makes oil, but I don't know if he's ever worked on a car or changed his own oil.

As a certified mechanic who knows other certified mechanics I can say most mechanics don't even know how viscosity grades work.

 

[cammyfive79]

I used all of those back in the day in the ‘90s. Duralube, Slick 50, Prolong, and I think there was one more.

Of course now we know that most are snake oils that dilute the add pack of a good oil, and any immediate benefit (chlorinated parrafins) doesn’t help, and may actually be detrimental, long-term.

After being obsessed with the informercial that played Saturday mornings, I bought Zmax for my lowly Plymouth Duster (not the cool one, the econo-box version) hoping it would cut my 0-60 in half. Haha.

 

[RedSpider]

I seem to remember that this was some problem with synthetic affecting the apex seals in the mazda rotary.

Correct. I have a book somewhere, probably buried in the attic by now, on the history of the development of the Rx7 (I've had a few). It specifically talked about this. The problem was, conventional oils did fine, but the automotive synthetics available at that time, of which there were very few, were tested and all did fine, except one. Rumored and suspected to be Mobil 1, but never publicly stated by Mazda. It caused the apex seals to not slide across the rotor housing, but to chatter. I.E., hop, skip, and jump across the surface, leading to uneven wear to both the housing surface and the seals. Mazda, not wanting to put themselves into the uncomfortable position of having to specifically recommend against any one synthetic oil brand, and not wanting to have to reengineer their seals and housing surfaces, decided to make the blanket statement "no synthetics in rotaries".

Doesnt seem to be a problem in the modern era, I have been out of the Rx7/Rx8 club for quite a while now, but 10-15 years ago plenty of people on the forums were using synthetics without any known issue.

 

[TiGeo]

Glad to see the urban legend I started back in HS is still going strong today.

 

[JohnnyG]

I used all of those back in the day in the ‘90s. Duralube, Slick 50, Prolong, and I think there was one more.

Of course now we know that most are snake oils that dilute the add pack of a good oil, and any immediate benefit (chlorinated parrafins) doesn’t help, and may actually be detrimental, long-term.

Wait a minute, you were supposed to use Prolong in engines?

 

[SOUNDMAN5000]

I'm the kinda person who wants the best for his car, truck and motorcycles at any expense. Yes, i'm older and know all the early talk and warnings about Synthetics but I wanted the best for my then almost new 90's EVO Harley.

After using mineral base 20w-50 motorcycle V-Twin oil the first year or so I decided to change to the then new on the market Mobil 1 V-Twin Synthetic 20w-50 and new filter. I changed it myself as I always do but at the first stop light i had a top end tic, tic, tic, the next and every stop light tic, tic, tic got back home after about 20 miles dumped the Mobil 1, refilled with mineral and no tic, now 27 years later not a drop of synthetic again and no more tic!

No misinformation or something I had a parts guy tell me, it was my first had experience, Mobil 1 Synthetic made my top end tic and tic loud, never used synthetic again in that bike and never heard a tic again, I still have the tic free bike!

 

[Tom NJ]

Just a little perspective on seal compatibility. Back in the 70s my employer (Hatco) was selling 100% diester based motor oils meeting SE/CC for rebrand. The major oil companies were pushing back against “synthetic” in the early years, and one item of contention was seal compatibility. In order to counter this, Hatco ran some comparative tests.

Using the specified seal materials and test methods, we compared our diester 10W-40 oil with Quaker State mineral oil 10W-40, one of the most popular mineral oils of the time. Knowing there was a lot of variabilities in seals, we purchased the seal materials by part number from different locations in the US in order to include seals meeting the same specification but made by different manufacturers.

As expected, the results showed that the ester based oil swelled seals more than the mineral oil. However, the results also showed that seals from different manufacturers with the same part number had greater variability in swell than between the ester and mineral oil. Once again, multiple variables cloud conclusions and lead to misconceptions.

I was responsible for customer technical support at the time and leakage complaints were rare. I don’t doubt that the cleaning and swelling effects of the 100% ester based oil uncovered some sludge clogged leaks and may have caused some, but swelled seals may have also closed some other leaks or potential leaks. In any case, no one currently recommends 100% ester or 100% PAO based motor oils as neither is healthy for seals.

The Mobil 1 at the time was based on a mixture of PAO and POE, but I doubt the 10-20% dosage of ester was materially responsible for the reported leakage/seeping issues they had. More likely the use of a 5W-20 oil in engines designed for 10W-40 played a greater role.

 

[Mackelroy]

Boomer 1964 and earlier

 

[Carlostrece]

The thread that never dies. Much like the topic itself.

 

[SimpleSyrup]

I was thinking back to the first car I bought myself around 1998 - a 1989 Accord LX 5spd (last year of the carbureted engine) - and taking it to the local Honda dealership for a tune up. They had 2 oil change services "standard" and "synthetic". I had no idea what the differences were so I asked and the SA told me that synthetic was "too slick" for cars like mine that had used regular dino oil for its 140K mile life. I recall him also saying that you had to use regular dino oil for the first 30K miles before you switched to synthetic and synthetic was really only to be used for "some sports cars". My memory is a little fuzzy as this was almost 30 years ago but I seem to recall that thought being widely circulated on the car forums that I visited in the very late 90s/early 2000s.

Was there any truth to any part of that? Any ideas on why that was conventional wisdom during that time period?

What you mentioned was something I often heard, usually by shops that didn't sell synthetic oil. I remember hearing how it would cause the engine to prolapse and leak oil like a spaghetti strainer if you use synthetic.

There's a lot more mechanics in the world that fancy themselves as engineering experts than there are engineering experts that fancy themselves as mechanics. The first group is more popular on YouTube these days. The latest fad over the past couple years is the whole "modern engines are designed to fail" "you have to use 5000 mile oil changes or it will grenade" and "0w-20 is too thin so use 5w-30."

 

[Carlostrece]

boomers to me is more or less anyone born before like 1980. That or they have the same mentality as someone born in 1920.

Yaaa, umm... Hmm. Based on what you just posted, you don't know the difference between Silent Gen, Boomers, or Gen X. I'm sure you know more about how it was back-in-the-day when we were young even though you weren't born yet.

 

[Carlostrece]

What I recall hearing was that you didn't want to break in your new engine using synthetic oil.

Yes that was commonly accepted knowledge back then, including among certified mechanics. My autoshop instructor taught us that in school. I don't know if it was correct info.

Also, the more 'sane' folk used to say, "It's good if you live in Alaska or Death Valley. Most people don't need it".

That was correct. The engineering designs of cars back in-the-day did fine with conventional oil in moderate climates. Often racking up 200k to 300K miles on conventional oil. Sometimes more.

There were few synthetic oils to choose from back then. In fact, Mobil 1 was the only synthetic oil most people had heard of and it was crazy expensive back then. It wasn't worth the price, IMO.

 

[Mechanician]

Yes that was commonly accepted knowledge back then, including among certified mechanics. My autoshop instructor taught us that in school. I don't know if it was correct info.

That was correct. The engineering designs of cars back in-the-day did fine with conventional oil in moderate climates. Often racking up 200k to 300K miles on conventional oil. Sometimes more.

There were few synthetic oils to choose from back then. In fact, Mobil 1 was the only synthetic oil most people had heard of and it was crazy expensive back then. It wasn't worth the price, IMO.

I worked with both VW, and Honda back in those days. And that was the information that came down from corporate technical instructors, and DSMs.
I still can't imagine why they would have passed along misinformation. It was a powerful urban legend,
I'm not sure where the board here got the more accurate information from.

 

[OVERKILL]

That was correct. The engineering designs of cars back in-the-day did fine with conventional oil in moderate climates. Often racking up 200k to 300K miles on conventional oil. Sometimes more.

The smogger cars with broomstick cams weren't hard on oil. Remember, the 1982 305 was 145HP, that's 29HP/L!

 

[4WD]

The smogger cars with broomstick cams weren't hard on oil. Remember, the 1982 305 was 145HP, that's 29HP/L!

Yep. And bet you knew someone with a 318 Mopar romping on 160 HP !!!