Synthetic oil is slicker and thinner than conv...

[Brule]

According to Greg Damon on KMOX today he told everyone:


-Don't switch a high mileage [165K] car to synthetic oil because it is slicker and thinner than conventional and may cause leaks.
-Don't go by your Honda OLM and just change conventional oil at 3000 miles or [recommended] synthetic oil at 6000 miles.


[Greg is an ASE certified Master Automobile Technician with an Advanced Level Specialist Certification (L1) in advanced engine performance. He also is an ASE Certified Undercar Specialist (X1) and is a Gateway Clean Air Program Recognized Repair Technician]

KMOX 1120AM is a powerful station based in St. Louis that can often [esp. at night] be picked up as far as the east coast.

KMOX Auto Show: Saturdays 4-6 pm central.

 

[MolaKule]

Greg Damon is not a Lubrication Engineer. Nuf said!

 

[FoxS]

The OLM was supposed to make it easier for the masses.

Oh well, I suppose mechanics know more than engineers.

 

[jrtribology]

I know one thing no matter what you use it will get dirty just as fast ...

 

[Pablo]

Originally Posted By: Brule
Automobile Technician

 

[Brule]

Whoops, on the internet I always forget to indicate somehow the irony or sarcasm I intend. So just to be clear, I'm not supporting Damon's claims and I'm not using his to back mine. I've done 10K OCI's for 80K miles now myself. That is, I think these are irresponsible statements from someone in authority that many people [not BITOGers] will blindly accept and follow.

 

[Danh]

Valvoline does not recommend synthetics for engines that have seal leaks, so there may be something to the idea that synthetics may leak more than conventionals. Which doesn't suggest synthetics actually cause leaks.

 

[Zaedock]

Not all mechanics think that way. It's unfortunate that he does. It's such a waste of oil.

 

[jrtribology]

Yes, I noticed on old synthetic oil container labels from different manufactures warned not to use it on vehicles made before 1980 because of the gaskets

 

[skyship]

I guess he is selling oil changes for a day job. Synthetic oil does not damage oil seals or gaskets BUT it often has good detergent levels and cleans well, so if your engine has a high oil consumption or some leaks already, removing sludge or varnish might make the leak rate worse.
In very general terms if you use cheap supermarket dino oil a typical OCI might be 5K miles max, if you use a major brand top quality dino or part synthetic the OCI might be 7.5K miles and if you use the latest high tech fully synthetic it might be extended to 10K miles.
The new oil service lights are good in terms of allowing for time at idle and stop starting and are very reliable.

 

[NHGUY]

Valvoline sent out a product sheet when their synthetics came out years ago,they did not recommend using it in 5 year old engines,unless all gaskets and seals were replaced first.

 

[Garak]

Originally Posted By: Danh
Valvoline does not recommend synthetics for engines that have seal leaks, so there may be something to the idea that synthetics may leak more than conventionals. Which doesn't suggest synthetics actually cause leaks.


I don't recommend synthetics for leakers, either, because synthetic is too expensive for regular top up.

 

[CourierDriver]

HomeBlogDefault Motor Oil 102


We left off discussing that a 0W-30 grade oil is not thinner than a 10W-30 oil. They both have the same thickness at operating temperature. The 0W-30 simply does not get as thick on cooling as the 10W-30. Both are still way to thick to lubricate an engine at startup.

I have heard several people say that Porsche specifically prohibits a 0W-XX engine oil, that it is too thin. Now here is the partial truth I spoke of earlier. We will discuss multi-grade oils. Earlier we said that a straight 30 grade oil has a thickness of 10 at the normal operating temperature of your engine. The multi-grade oils 0W-30 and 10W-30 also have a thickness of 10 at 212°F.

The difference is at 75°F, your startup temperature in the morning.

Oil Type Thickness at 75° F Thickness at 212° F
Straight 30 250 10
10W-30 100 10
0W-30 40 10
Straight 10 30 6
( Oil Type varying Thickness )

Now you can see that the difference between the desired thickness your engine requires ( = 10 ) is closest to the 0W-30 oil at startup. It is still too thick for normal operation. But it does not have far to go before it warms up and thins to the correct viscosity. Remember that most engine wear occurs at startup when the oil is too thick to lubricate properly. It cannot flow and therefore cannot lubricate. Most of the thick oil at startup actually goes through the bypass valve back to the engine oil sump and not into your engine oil ways. This is especially true when you really step on that gas pedal. You really need more lubrication and you actually get less.

Note that a straight 10 grade oil is also too thick for your engine at startup. It has a thickness of 30. Yet at operating temperatures it is too thin having a thickness of 6. It needs to be around 10. The oil companies have added viscosity index improvers or VII to oils to solve this dilemma. They take a mineral based oil and add VI improvers so that it does not thin as much when it gets hotter. Now instead of only having a thickness of 6 when hot it has a thickness of 10, just as we need.

The penalty is the startup thickness also goes up to 100. This is better than being up at 250 as a straight 30 grade oil though. Oil with a startup thickness of 100 that becomes the appropriate thickness of 10 when fully warmed up is called a 10W-30 grade motor oil. This is NOT as thick as a straight 30 grade oil at startup and it is NOT as thin as a straight 10 grade oil at full operating temperature.

The downside of a mineral based multi-grade oil is that this VII additive wears out over time and you end up with the original straight 10 grade oil. It will go back to being too thin when hot. It will have a thickness of 6 instead of 10. This may be why Porsche (according to some people) does not want a 0W-30 but rather a 10W-30. If the VII wears out the 0W-30 will ultimately be thinner, a straight 0 grade oil. When the VII is used up in the 10W-30 oil it too is thinner. It goes back to a straight 10 grade oil. They are both still too thick at startup, both of them. The straight 0 grade oil, a 5 grade oil and a 10 grade oil are all too thick at startup.

This is just theory however. With normal oil change intervals the VI improver will not wear out and so the problem does not really exist. In fact, oils do thin a little with use. This is partly from dilution with blow by gasoline and partly from VI improvers being used up. What is more interesting is that with further use motor oils actually thicken and this is much worse than the minimal thinning that may have occurred earlier.
Synthetic oils are a whole different story. There is no VI improver added so there is nothing to wear out. The actual oil molecules never wear out. You could almost use the same oil forever. The problem is that there are other additives and they do get used up. I suppose if there was a good way to keep oil clean you could just add a can of additives every 6 months and just change the filter, never changing the oil.



When the additives wear out in a synthetic oil it still has the same viscosity. It will not thin as a mineral oil. The fear that some say Porsche has that oils thin when the VII runs out is not applicable to these synthetic oils. These oils will always have the correct thickness when hot and will still be too thick at startup as with all oils of all types, regardless of the API / SAE viscosity rating.

Automotive engine manufacturers know these principals of motor oils. They know there is thinning or thickening that will occur. They take these things into account when they write that owners manual. Mineral oil change recommendations will generally include shorter time intervals than those of synthetic oils.

The reality is that motor oils do not need to be changed because they thin with use. It is the eventual thickening that limits the time you may keep oil in your engine. The limit is both time itself (with no motor use) and/or mileage use. The storage of motor oil in your garage, particularly mineral based oils, slowly ages the oil limiting its use later. Do not store huge volumes of oil in your garage that is exposed to extremes of temperature.

Chapter Three
Chapter One

Tags: Motor Oil


Motor Oil 101
Motor Oil 102
Motor Oil 103
Motor Oil 104
Motor Oil 105
Motor Oil 106
Motor Oil 107
Motor Oil 108
Motor Oil 109
Motor Oil 201
Motor Oil Mid-Term Exam
Motor Oil Final Exam

 

[whip]

And yet when a person on the internet starts spewing advice about how to break in an engine, or what oil is best, it's taken as gospel........

 

[aquariuscsm]

Originally Posted By: CourierDriver
The downside of a mineral based multi-grade oil is that this VII additive wears out over time and you end up with the original straight 10 grade oil.

When the additives wear out in a synthetic oil it still has the same viscosity. It will not thin as a mineral oil.


This is what confuses me about syn vs dino. Would this only apply to a pao/ester vs a dino,since grp III syn is dino/mineral oil? I`m trying to understand what the difference is in say,GTX vs Syntec. Do they have identical add packs,with the only difference being that Syntec is *de-waxed*?

 

[Sayjac]

Quote:
I guess he is selling oil changes for a day job......

Seems likely. Damon's got multiple titles/certs but as pointed out, Lubrication Engineer is not one of them.

 

[aquariuscsm]

So do synths and dinos privide identical wear protection?

 

[LeakySeals]

Originally Posted By: aquariuscsm
So do synths and dinos privide identical wear protection?
At 3k probably. At 5k maybe. At 7k probably not. But there are many variables beyond oil chemistry to consider so nobody can really say conclusively. No at 10k is more conclusive I suppose.

 

[Garak]

Oh oh, that's a loaded question. My take is that with equivalent oils (i.e. a good conventional versus a good synthetic, keeping PQIA alert oils out of the equation), over appropriate OCIs and if the oils are specified for the application, sure.

If you're dramatically extending OCIs or if the vehicle calls for a synthetic only, that may be a different matter. However, they may specify synthetic only because of an OCI concern, and not any performance metric.

So, an average, normally aspirated engine under normal climate conditions and normal driving conditions needing a 5w-20 or 5w-30 SN/GF-5 for something like a 3750 mile OCI isn't going to see better wear protection from a synthetic 5w-20 or 5w-30. The synthetics do offer better viscosity choices (i.e. a 0w-20 or 0w-30 versus the 5w-20 or 5w-30, or a 0w-40 or 5w-40 versus a 15w-40).

Guys like tig1 run his vehicles forever on 10,000 mile M1 OCIs. I ran cabs for hundreds of thousands of miles using conventional with 6,000 mile OCIs. Six of one or half dozen of the other if you ask me.

Also, read Dave Newton's paper on the matter on the main page.

 

[skyship]

Originally Posted By: NHGUY
Valvoline sent out a product sheet when their synthetics came out years ago,they did not recommend using it in 5 year old engines,unless all gaskets and seals were replaced first.


Valvoline are a good company and one of the few all American companies that manages to sell engine oil in Germany, apart from Mobil.
They are being over cautious to make such a statement and I always tell anyone who asks me that if their engine has a high oil consumption or any leaks, don't change to a full synthetic, think about changing to a major brand HM oil insted.
My own 1.9 diesel had no leaks and a low oil consumption at 160K km, and I changed to a G4 Synthoil without any problems. My oil consumption fell from 0.5 to 0.3 ltrs per 10K km OCI, probably due to the lower evapourative losses from a good full synthetic, BUT DYOR as engine every engine is different.