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synthetic oil

Started by G.Lucas #25354, January 06, 2008, 09:28:40 AM

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G.Lucas #25354

I am sure this topic has come up before. How offen should synthetic oil be changed? On new cars and on old collector cars? Some people I talked to change there oil on new cars every 20,000 miles. They use the long life oil filter.I think thats a bit long.Granted it depends on driving conditions. On collector cars with low use, once a year before going into storage. Synthetic oil does not hold moisture lkie traditional oil, I was told. I guess it comes down to what your comfortable with.What are the opinions of the club members? George.

TJ Hopland

I think a reason new cars can go longer is just the better control or tune the computers can maintain and because of that control they are able to tighten up tolerances which also helps keep the oil cleaner.  On older engines I would just stick with the original recomendations.  Newer oils could be better for thermal breakdown but I dont see any way they will reduce contamination especially on pre PCV motors.  Motor oil is still one of the cheapest parts of owning a car even if you change it too often.

I have had many people tell me to stay away from full synths in non regular use motors.  I dont remember why but it seemed logical at the time it was explained. The blends are supposed to be good.  Marine people talk about it a lot.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Johnny F #662

Quote from: TJ H on January 06, 2008, 12:34:49 PM
I think a reason new cars can go longer is just the better control or tune the computers can maintain and because of that control they are able to tighten up tolerances which also helps keep the oil cleaner.  On older engines I would just stick with the original recommendations.  Newer oils could be better for thermal breakdown but I dont see any way they will reduce contamination especially on pre PCV motors.  Motor oil is still one of the cheapest parts of owning a car even if you change it too often.

I have had many people tell me to stay away from full synths in non regular use motors.  I dont remember why but it seemed logical at the time it was explained. The blends are supposed to be good.  Marine people talk about it a lot.

I believe the main reason that synthetic oils are not recommended in older engines, has something to with their molecular makeup, which causes the oil to leak, where traditional oil doesn't.  In many discussions of synthetics, the general consensus is that its really not needed and might even be overkill.  Myself I have a 85 Eldo, and was advised to use synthetic about 7 years ago.  I went half way and use a semi synthetic.  I think the main consideration with any type of oil used, is frequent oil changes, as the oil cleans the internal engine, and changes gets rid of dirt.

Mike Josephic CLC #3877

Johnny is right on the money for this topic.

Synthetic oils for our engines are overkill and serve no advantage vs.
regular oils.  Best advice is to change your oil annually, in spring before car show
season.  Condensation (moisture) will collect in the bottom of your oil pan upon
storage regardless of which oil you use.  Since our cars sit almost 4-6 months out
of the year, change the oil (and filter) annually with a good API certified oil and
forget about the expensive alternatives.  They will not do anything for you.

After all, we don't drive racing cars!!

Mike
1955 Cadillac Eldorado
1973 Cadillac Eldorado
1995 Cadillac Seville
2004 Escalade
1997 GMC Suburban 4X4, 454 engine, 3/4 ton
custom built by Santa Fe in Evansville, IN
2011 Buick Lucerne CX
-------------------------------------
CLCMRC Museum Benefactor #38
Past: VP International Affiliates, Museum Board Director, President / Director Pittsburgh Region

homeonprunehill

Quote from: G.Lucas on January 06, 2008, 09:28:40 AM
I am sure this topic has come up before. How offen should synthetic oil be changed? On new cars and on old collector cars? Some people I talked to change there oil on new cars every 20,000 miles. They use the long life oil filter.I think thats a bit long.Granted it depends on driving conditions. On collector cars with low use, once a year before going into storage. Synthetic oil does not hold moisture lkie traditional oil, I was told. I guess it comes down to what your comfortable with.What are the opinions of the club members? George.

01-06-08
GEORGE, I hate to be the bearer of bad news, But, just as there is no Santa, Easter Bunny or Tooth-Fairy, the same goes for "Synthetic" motor oil.  Go to googe search engine and type in "Car Craft's"test of "synthetic"motor. Read para. 5. The reason it is not used in older engines is that it does not contain the correct additives.  As far as how often one should change oil, I'VE known two(2) people that NEVER change the oil (In the normal sence of changing oil and filter. Fifters were changed about every 2-3 thousand Miles and oil topped off. Niether car was "babbied"and traded-in at over 100 thousand on the speedo. I'M thanking of installing a "magnetic" oil drain plug in my car's engine. Any thoughts about that?
Good Luck,JIM   
USED,ABUSED AND MISUSED CADILLACS AND LA SALLES

Mike Josephic CLC #3877

Jim:

A quote from the same "Car Craft" article is below.  Whether the oil you use is synthetic or natural, you have to change it for the reasons outlined below.  To advise otherwise does a disservice to the readers of this forum.  It's the additive package that becomes depleted upon use and time, it matters not what the "base-stock" is.  I stand by my recommendation to change oil & filter at least annually in our cars.

QUOTE:

"For street engines that do not suffer this kind of track-day abuse, merely pouring in a synthetic does not mean that you can radically extend service drain intervals. Petroleum-based oils do not lose their base lubrication characteristics, what does suffer with use are the additive packages added to the oil. Synthetics are no different. Engines that see only limited use and ones that may never get up to full operating temperature can suffer from high levels of contamination that will require shorter drain intervals.For example, Farner says that for every pound of fuel burned in an engine, the combustion process also creates a pound of water. Some of this water will eventually end up in the oil pan. If the engine rarely sees sump temperatures that exceed 212 degrees F (water's boiling point), the water quickly mixes with another combustion byproduct--sulfur--to create acids that can eventually eat bearings if the oil is not drained."

I rest my case,

Regards,

Mike

1955 Cadillac Eldorado
1973 Cadillac Eldorado
1995 Cadillac Seville
2004 Escalade
1997 GMC Suburban 4X4, 454 engine, 3/4 ton
custom built by Santa Fe in Evansville, IN
2011 Buick Lucerne CX
-------------------------------------
CLCMRC Museum Benefactor #38
Past: VP International Affiliates, Museum Board Director, President / Director Pittsburgh Region

Bill Gauch #23121

Quote from: homeonprunehill on January 06, 2008, 11:37:43 PM
01-06-08
GEORGE, I hate to be the bearer of bad news, But, just as there is no Santa, Easter Bunny or Tooth-Fairy, the same goes for "Synthetic" motor oil.  Go to googe search engine and type in "Car Craft's"test of "synthetic"motor. Read para. 5. The reason it is not used in older engines is that it does not contain the correct additives.  As far as how often one should change oil, I'VE known two(2) people that NEVER change the oil (In the normal sence of changing oil and filter. Fifters were changed about every 2-3 thousand Miles and oil topped off. Niether car was "babbied"and traded-in at over 100 thousand on the speedo. I'M thanking of installing a "magnetic" oil drain plug in my car's engine. Any thoughts about that?
Good Luck,JIM   

I got a "lesson" when I was 15 years old from a guy who worked the parts desk at a local dealer. He had a Styrofoam cup covered by another Styrofoam cup that he wanted to show us. Apparently, a woman had her three year old car towed in not working. The engine was totally seized. They dropped the pan and found it almost full of sludge, which is what was in the cup. After asking her how frequently she changed the oil, she said she added oil whenever it got low. She didn't know that she was supposed to change it.

Personally, the only car I would not "change" the oil on would be a $500 beater that leaks a quart a week. Changing the filter every 3-6 months and topping off the oil would be fine because the car is essentially changing its own oil at the expense of the environment.  :o
WANTED: Nothing right now.

- 1938 Series 65 - 4-door sedan - Restoration (slowly) ongoing

http://38caddy.blogspot.com/

David #19063

Maybe my memory is failing...

But I think I remember when synthetic oil first came out, they were saying the benefit was it would last for 50,000 miles or better.

Of course, there also was the 100,000 mile before the first tune-up promise too.

And when the Ford Five Hundred came out, Ford swore up and down that it was not a new Taurus or the Taurus replacement...however, the Five Hundred is now called the Taurus.

It all makes me wonder.

Hmmm...
David #19063
1996 DeVille Concours

Perry G

OK,,, Hear is my story.  I bought a 88 eldorado with 72k on it years back for the wife. I started using synthetic oil in it on the first change I did. I did know that after changeing to synthetic it will brake down the sluge buildup and plug oil ports. Well it never did plug any ports but it did clean the hell out of the lower end. So much so it started leaking oil on the shop floor. I tightend up all the pan bolts which helped some but she still leaked. Changed back to non synthetic oil and the problem went away after about 15k. the car now has 146k on her and she leaks only when I pull the plug..

G.Lucas #25354

Appearnty synthentic oil does not allow the seals to expand as much as regular oil. This is why oil leaks occur on older vechicals. It is also recommended that you use either full synthetic or full regular and not a blend.I do not know why this is.I think that using synthetic oil once in awhile to help clean out the motor is a good thing. I was told once buy a mechanic that he use to put transmission oil in the engine and run it for 20 min and replace the oil and filter with regular oil. Apparently this cleaned out the motor of all the sludge and left it clean on the inside.I have never tried this,and don't recommend it.

Mike Josephic CLC #3877

Quote from: G.Lucas on January 09, 2008, 09:34:59 PM
Appearnty synthentic oil does not allow the seals to expand as much as regular oil. This is why oil leaks occur on older vechicals. It is also recommended that you use either full synthetic or full regular and not a blend.I do not know why this is.I think that using synthetic oil once in awhile to help clean out the motor is a good thing. I was told once buy a mechanic that he use to put transmission oil in the engine and run it for 20 min and replace the oil and filter with regular oil. Apparently this cleaned out the motor of all the sludge and left it clean on the inside.I have never tried this,and don't recommend it.

Back in the 60's when I worked for Gulf Oil we had something called "flushing oil" which was a blend of 10W oil and kerosese.  We used to recommend this to folks who didn't change oil on a regular basis.  I cleaned out many a dirty engine with this stuff.

However, I would not recommend any such thing with today's oils.  They are carefully formulated to do their job.  All you need to do is change them (especially for our cars driven sparingly) once per year and also change the filter. This recommendation is independent of mileage, in other words, even if only driven a few hundred miles per year. That will eliminate a host of problems -- especially future problems.  Mike
1955 Cadillac Eldorado
1973 Cadillac Eldorado
1995 Cadillac Seville
2004 Escalade
1997 GMC Suburban 4X4, 454 engine, 3/4 ton
custom built by Santa Fe in Evansville, IN
2011 Buick Lucerne CX
-------------------------------------
CLCMRC Museum Benefactor #38
Past: VP International Affiliates, Museum Board Director, President / Director Pittsburgh Region

Johnny F #662

Quote from: G.Lucas on January 09, 2008, 09:34:59 PM
Apparently synthetic oil does not allow the seals to expand as much as regular oil. This is why oil leaks occur on older vehicles. It is also recommended that you use either full synthetic or full regular and not a blend.I do not know why this is.I think that using synthetic oil once in awhile to help clean out the motor is a good thing. I was told once buy a mechanic that he use to put transmission oil in the engine and run it for 20 min and replace the oil and filter with regular oil. Apparently this cleaned out the motor of all the sludge and left it clean on the inside.I have never tried this,and don't recommend it.

Using transmission fluid, (I really don't believe its an oil, in the true sense of the word), in the engine is an old mechanics trick.  Transmission fluid acts as an detergent, and will clean internal parts.  Try it on your hands the next time they get greasy and oily.

I have been using a semi synthetic in my '85 Eldo for almost 8 years and so far so good.

wm link

The reason regular oil turns "Black" is that the scortch or burn temp of regular oil is easily reached during normal engine operation. Once the oil burns... its leaves black carbon and thats an abrasive.  Synthetics are not only slipperier but they also 'burn' at MUCH higher temps. This ability to resist burning nearly eliminates the production of abrasive carbon and this is the reason the change intervals are increased in normal  synthetic usage. The older 'rope' style seals could have added difficulty holding back synthetics because they are SO slippery.   With many of the needed protective additives (zinc)  now removed from  conventional oils, and lead from gasoline makes a synthetic a much better choice provided you can effectivly keep it in the engine...in my opinion.