AZ manager says synthetic kills old engines

[MisterBrian]

The store manager of my local AutoZone insists if I switch to fully synthetic motor oil in an engine with a lot of miles on it, it may dislodge crud and blow the engine. I know you don't have to have a degree in lubricity to manage an AutoZone. I also figure they attend liability reduction seminars.
His theory sounds like complete hogwash to me.
Tell me he's full of it.

 

[bigwillie]

From all of the information I've gained through this board, and all of the things I've heard about synthetic oil I would say he's full of B.S. Please don't listen to the poor uneducated AZ guy. The only thing synthetic might do is because of it's extra cleaning properties is clean a false seal and your car might leak a little. If you wan't to switch to synthetic, do it and be happy. You might want to try some auto-rx first just to make sure your engine is squecky clean, but I'm sure you'd have no problem switching to synthetic if you want to.

 

[Bob Miller]

While there is a remote pssibility of any high quality oil dislodging "accumulated stuff" its not unique to synthetics in my humble opinion.

You might consider using one of the sponsors products (of this web location) to give your engine a cleaning first.

 

[Terry]

He not full of it, he's empty.

I slept at the Holiday Inn Express last night but I do not claim to be a Autozone Manager or have the needed skill set to fake it......uh he don't know what he's talkin bout.

I'm sure that he is sincere and trying to keep you from cratering that engine.

Most oils now have a fairly large "syn" component so most OTC lubes would damage the engine if his theory was correct.

I do agree that many high mileage engines have sludge precursers or elevated levels of deposits and once they let go it can cause problems.

 

[MisterBrian]

He not full of it, he's empty.

Hah!
Well, thank you guys for laying his FUD to rest. I'll just remove the oil filler neck and see if my pinky can find sludge in the valve cover. If so, motor flush, filter change, then synthetic.

 

[nemir]

I think a lot of input about switching from dino to syn [2005]is being parralled with the switch from non-deturgent to full deturgent[1958].

 

[vvk]

Well, if you are talking about a Subaru, then there is no reason to use anything but non-synthetic. Subaru specifically prohibited using synthetic in their engines until only a few years ago when they finally reluctantly allowed it. The new SAAB 9-2x owners manual has a specific mention about the car (aka Subaru Impreza) using non-synthetic motor oil, unlike other SAAB models.

Also, if you look at oil analysis results, you will see that non-synthetics clearly produce lower wear.

 

[Pablo]

quote:

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Also, if you look at oil analysis results, you will see that non-synthetics clearly produce lower wear.

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Interesting.

For every engine mfr that "prohibits" synthetic oil (not many) - there are at least 2X that encourage or even specify synthetic oil use.

As for AZ manager training. I have no idea how many of their mandatory tribology courses include automobile crankcase lubrication with synthetic oil lab class time.

 

[oilyriser]

I didn't see any prohibition against synthetic in the three Subaru owner's manuals I've read (1992, 1999, 2001).

 

[Chris142]

I think A-Zone hires the most incompetent people they can.

 

[Audi Junkie]

He should cite verifiable examples of the "crud effect".

 

[z917990]

I agree with the other posters. Synthetic should be OK. However, please look at high mileage oils that do a really good job and are usually less expensive than full sythetic. Valvoline Maxlife, for example, has been shown to be an excellent oil, is partially synthetic and costs about $2.38 at Wally World, as opposed to Mobil 1 which usually goes for about $5.00 a quart.

 

[vvk]

quote:

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Originally posted by oilyriser:
I didn't see any prohibition against synthetic in the three Subaru owner's manuals I've read (1992, 1999, 2001).

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That's right, nothing in owner's manuals. But they did issue several TSBs on this issue.

 

[Warstud]

quote:

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Originally posted by MisterBrian:
The store manager of my local AutoZone insists if I switch to fully synthetic motor oil in an engine with a lot of miles on it, it may dislodge crud and blow the engine. I know you don't have to have a degree in lubricity to manage an AutoZone. I also figure they attend liability reduction seminars.
His theory sounds like complete hogwash to me.
Tell me he's full of it.

---

I'm sure in some cases it may have happened before in some high mileage neglected sludged vehicles. Same with changing tranny fluid with HM vehicles that probably never had the fluid changed under 100k.

 

[T-Keith]

I've heard this theory many times before, but in order for it to be true two things have to happen.

First you have to have enough large chunks of crud to dislodge and just saying it's high mileage doesn't fit this bill for me. These chunks also have to be in the correct location to be "in front" of a oil passage or wear surface, but "after" the filter.

Second, the "synthetic oil" has to have the abilty to quickly dislodge the crud. I don't think any of the major synthetic brands has such a capability, or at least in any large extent greater then a "dino" oil.

-T

 

[J. A. Rizzo]

The AutoZone manager might have been thinking of another phenomenon. Maybe in an engine that was designed for and run with non-detergent motor oil, it could cause a problem if you use a detergent oil all of a sudden. That would dislodge all sorts of goop. I know that in older VW microbuses, there was no oil filter, just a screen, and the engine was designed for use with non-detergent oil. If you put detergent oil in them after they had lots of miles on non-detergent oil, it could clog up the screen pretty fast and the engine would either overheat or seize up.

So, it sounds like he has good intentions, but might not have all the facts straight. The real question is whether or not there is any benefit to using synthetics in the older engine you have. That depends on all sorts of things, and I don't know the answer. Just wanted to chime in on the manager knowledge question.

 

[q2bruiser]

My local says Aliens kill engines.

 

[BIGJ552000]

Hey, MisterBrian, which Autozone in Buffalo did you go to?

 

[439SW]

I switched from dino to full synthetic in my 1980 Chevrolet pick-up about a year ago.It has a 1978 Olds 350 engine in it and I switched after it had used dino for 26 years. no problems whatsoever. Only difference I noted was it seemed less "cold natured" after switching to synthetic.
Unfortunately it still gets the same 10 miles per gallon of gas.

 

[k1xv]

The only thing that I heard of that sounds remotely possible is that deposits near oil seals may be dissolved, and when that occurs, an already compromised seal may leak more oil than it did before.

Also, when a change is made to synthetic, it is sometimes to a lower viscosity oil, which can increase the rates of leakage.