When Should I Start Using High Mileage Oil

[Texas Jim]

Like the title says...

I am looking for input and thoughts on high mileage oil.

My car now has a little over 90,000 on it and runs flawlessly... So far..

Just came back from a 10 day...4,500 mile trip.

Texas to South Georgia...up to the Outer Banks of N. Carolina, then to Richmond Virginia, then to NE Ohio, back down to E. Kentucky, and then back home.

From E. Kentucky to Ft Worth was a little over 925 miles.

Made a hard run from E. Kentucky to Ft. Worth.

Most of the time was around 100... :)

Oil was at about the same level when I got back as it was when I left.

I have "NEVER" had to add any oil between changes.

I have gone as far as 10,000 miles between changes, but usually change it around 7,000 miles.

If I have ran it REALLY HARD.. I will change it at 5,000 miles.

It is usually about a half quart low when I have it changed.

I am kinda of the mind that "If It Ain't Broke...Don't Fix It"...

But I hear so much about the High Mileage oils...that I just wanted some input from some of y'all.

Any and all comments welcome...

[JimD]

Like the title says...

I am looking for input and thoughts on high mileage oil....

I am kinda of the mind that "If It Ain't Broke...Don't Fix It"...

.But I hear so much about the High Mileage oils...that I just wanted some input from some of y'all.

Oil company marketing can be seductive.

Put your faith in the GM powertain engineers; that would be the folks that conducted extensive high mileage/high RPM tests before they certified the engine for the oil they recommended. We have no idea what testing the oil companies have completed.

And the term "high mileage" is a little slippery. For me, high mileage is now at the 199,000 mile mark and I got there without the use of high mileage oils.

[stsevillests]

I don't know for sure, high mileage oil could be a marketing scam. I'm 41 and my dad always used Valvoline when I was a kid, always told me to stay away from Quaker State. Well one day at Advance Auto they had an oil change special for Castrol, so I started using Castrol GTX, 5 quarts - $16.99 plus filter. Several oil changes later I moved to Castrol GTX High Mileage for $19.99 with filter. Every month the filter brand changes. Autozone has the special on the months that Advanced don't. Sometimes it's the 5 quart jug + and I have 3 extra Bosch filters on the shelf waiting as I buy 3 specials, (2 cars) at once since I need 7.5 quarts for the caddy. The bottle says for engines over 75,000 Miles. Also claims

- 17% superior oil burn off protection versus the leading conventional oils in laboratory tests

- seal conditioners to help reduce leakage

- unigue technology to protect against wear and harmful deposits

- Proprietary additives to minimize compression loss and maximize engine protection

Maybe it is BS, but I am buying it.

I ran Advance Auto brand oil in other cars/lawn mowers when I was trying to save money and I see people swear by Walmart oil. The trick is to change it before it gets worn down or dirty.

I'm still buying Castrol even though I live in Florida after the BP oil spill, others are not.

Bottom line, I always think the car seems to run better after an oil change regardless of the brand, but that may be in my head.

[Cadillac Jim]

If the engine runs better after an oil change, the rings may be sticking a little. I would use 10W-30 or 5W-30 oil recommended by GM, i.e. the American Petroleum Institute certified for use in automobile engines, as marked by the starburst symbol on the cans, usually on the top (1997 FSMM, pages 0B-3, 0B-4). IT looks like a big gear, with "American Petroleum Institute Certified" around the periphery and "For Gasoline Engines" in the center.

Beyond that, everybody has his/her own opinion and preference. There is no mention of high-mileage oil in the owner's manual. The cylinder bores on Northstar engines don't wear, and plain bearings don't wear on any engine under normal conditions, so I see little point in it. Some people say that it has seal softeners in it and thus may help keep the crankshaft and camshaft seals pliable, but when I look at the find print I see things like higher viscosity, intended to help keep compression up in worn cylinders and slow leakage down valve guides and such, and that's not for my engines. The FSM plainly states that 20W-40 or any other higher viscosity oil than 10W-30 is NOT to be used in Northstar engines and may damage them, and "higher viscosity" edges toward that.

[CarlaValentine]

My Eldo just passed 165k miles. My boyfriend and I put over 500 miles a week on it. I have only used Quaker State 10w30. I was considering changing to a high mileage oil on my next oil change, which is coming due in the next couple weeks, but after reading the post above me where it was stated that the FSM says NOT to use a higher viscosity oil I am re-thinking that idea. I only considered the switch because it developed a pretty bad oil-leaking habit after my last oil change...which started right after my not-so-mechanically-inclined boyfriend over-filled the oil by 2 quarts and drove it 60 miles. I have had to add over 3 quarts since my last oil change and figured maybe the high mile oil would help a little with the leak... but I think now I'll stick to the recommended 10w30...even if it costs me an extra quart or 3 between changes.

What I am wondering though, is this: High mileage oil is said to be higher viscosity than conventional oil, but the 10w30 rating is made based on viscosity...so would 10w30 high mile oil be more viscous than conventional 10w30, making it more like 20w40 or somewhere around there? Or do they take into consideration when making the rating that it is more viscous than conventional oil and add that into the equation? I'm not sure if that makes any sense to anyone, but I can't find a better way to state it.

[stsevillests]

If the engine runs better after an oil change, the rings may be sticking a little. I would use 10W-30 or 5W-30 oil recommended by GM, i.e. the American Petroleum Institute certified for use in automobile engines, as marked by the starburst symbol on the cans, usually on the top (1997 FSMM, pages 0B-3, 0B-4). IT looks like a big gear, with "American Petroleum Institute Certified" around the periphery and "For Gasoline Engines" in the center.

Not sure I ever bought a quart of oil of any brand in the USA without that symbol

[adallak]

Any motor oil is good for a high mileage Northstar as long as it is cholesterol-free and kills 99% of bacteria.

[KHE]

Save your money - just use regular engine oil as JimD stated. I sold my '96 Seville last week and it had 148,000 miles on it. All with regular conventional oil.

[Cadillac Jim]

CarlaValentine raised an interesting point: what about case half leaks? I've read recently that they are caused by seepage through the gasket, which might be helped by seal softeners, and I've read that they are caused by * dissolving* of the gasket sealer, which would be made worse by seal softeners. Most or all high-mileage oils have seal softeners in them so this is important. Not to mention those who use Marvel Mystery Oil or a can of ATF with an oil change. Anyone with something definitive here?

Another issue raised by CarlaValentine and stsevillests is that if the high mileage oil has the starburst symbol on it and is rated at 10W-30, is should be OK, shouldn't it? The viscosity ratings of oil have a range of measured viscosity at temperature associated with each number, and high mileage oils that advertise "higher viscosity" are more likely to be on the higher end of that range. But, if they are within that range and the viscosities are consistent with the ratings 10W-30, then their use will not "void the warranty."

[rustyboltz]

My 2 cents on this subject is to NOT to use the high milage oil. I have a Deville that currently has 178,765 miles on it and is still purrring like it should. I use Castrol 10-30 and change it every 3,000 miles. I had a GMC Sonoma that had 160,000 several years ago and I put some of the high milage oil in it on a oil change and the truck leaked it out so bad that I ended up with oil all over under the truck. I changed it back to regular 10-30 oil and it went back to its same ole reliable vehicle. From my opinion, do not change what you are doing if you want to keep the vehicle in good shape.

[KHE]

The case half seal will rarely leak bad enough to drip on the ground. It will seep oil but that is about it. The oil distribution plate that is between the oil pan and the lower case half will leak to the ground with age and miles. Many people confuse the oil distribution plate leak with the case half.

[JohnnyG]

Any and all comments welcome...

NEVER If you want to do something nice for your engine, get some GF-5 in it at your next oil change.

[JohnnyG]

I only considered the switch because it developed a pretty bad oil-leaking habit after my last oil change...which started right after my not-so-mechanically-inclined boyfriend over-filled the oil by 2 quarts and drove it 60 miles. I have had to add over 3 quarts since my last oil change and figured maybe the high mile oil would help a little with the leak... but I think now I'll stick to the recommended 10w30...even if it costs me an extra quart or 3 between changes.

Carla, this is probably the single worst thing that can happen to a Northstar. Overfilling this engine causes the excess oil to be sucked out through the PCV sytem and burnt in the combustion process, the result is usually stuck rings and an ongoing cycle of oil burning that only perpetuates the problem. I NEVER fill my engine to the full mark, about halfway is good enough and if it ever gets a little too low, the monitor will tell you. Try some WOT's, and get some (I hate to say this again) GF-5 into it as soon as you can, maybe you can reverse that process.

What I am wondering though, is this: High mileage oil is said to be higher viscosity than conventional oil, but the 10w30 rating is made based on viscosity...so would 10w30 high mile oil be more viscous than conventional 10w30, making it more like 20w40 or somewhere around there? Or do they take into consideration when making the rating that it is more viscous than conventional oil and add that into the equation? I'm not sure if that makes any sense to anyone, but I can't find a better way to state it.

Jims_97 is correct, and actually another reason to stay away from the HM hype. If the oil is thicker yet has to stay within the prescribed viscosity range, just how much thicker can it REALLY be? I'd say not much. His other point about the seal swelling additives is equally important, why would you want to soften and swell elastomer seals if they are not leaking? Just to promote premature wear I suppose....!

All of these selling points offer nothing but headaches for engines that are running good already, don't do it.

[Texas Jim]

Well, boys and girls...

I want to thank all of you very much.

Y'all have confirmed what I was thinking...keep the "SNAKE OIL" out of my car..

There will be nothing going in my DTS but the usual Mobil 1.

That is what it has always had in it.

It uses absolutely "NO OIL" at this time, with 90,000 miles on it.

As far as I know, there is also no leaks.

There has never been a drop of oil on the garage floor.

So...like I said in my very first post...

If the darn thing "AIN'T BROKE"... don't "FIX IT".. ...

Y'all reinforced this very well.

I "WILL" look into the GF-5 oil.

I will do some reading up on it.

Thanks again to everyone.

I am still listening to the great discussion....keep it going..

[Texas Jim]

Just a couple of added comments...

As some of you may know by now...my NorthStar does "NOT" get babied around.

Of course I don't abuse it...but I do "DRIVE IT" somewhat spiritedly at times.

It is not unusual for it to driven on long road trips in the triple digit range... sometimes for most of the day.

So far the powertrain has been totally flawless from day 1.

The "SOUND" of the NorthStar still thrills me when it is winding towards 7000 RPM...which is the shift point for it to change gears.

As a few of you may remember, I had the engine computer and the transmission computer "TUNED" about 3 years ago.

I then bought the whole software package to do some more "TWEAKING" on it.

I really, really, like my Cadillac.. ...and it likes to eat ricers...

Thanks for listening...

[Jan Olsson]

There is absolutely no need for you to start using any kind of high-mileage oil.

The main difference between a high-mileage oil and a "standard" oil is the larger amount of ZDDP or equivalent used in the high-mileage oils.

I remember the guru talking about them when he gave me some oil recommendations. Only earlier Northstar engines for instance (they had no roller followers for the cams instead flat tappets) and engines with distributors and gear type oil pumps need the higher ZDDP level (high mileage oils, oils suitable for diesel AND gasoline engines and oils with older classifications per API, i.e. SG/SF etc.). Your engine is fine with the manufacturer recommendations.

If an engine calls for an older API standard use the older standard. If you can't easily get what you are looking for, use an oil suitable for gasoline and diesel engines (with the right API classification). If you cant find one then you can start looking at the high-mileage oils.

[mike27513]

One source for good info on Oils is "Bob is the Oil Guy" site.

My preference is manufactured synthetic oil [most any brand] since it is more uniform and has fewer contaminants than refined "dino" oil and typically will perform better with less breakdown in High RPM use. My 04XLR 4.6 Northstar specs Mobil 1 Synthetic so I know that the Caddy engineers proved out this one in performance applications. In my 03 DHS I use Synthetic 5W-30 as well as the rest of my vehicles with no problems. My family drives over 100K per year [ 2 Adults, 2 teenagers] and I get to be the full time mechanic on our 5 vehicles.

Since your car is running fine with no leaks, etc. I would keep away for High mileage oils with additional additives [ contaminants?].

[Jan Olsson]

One source for good info on Oils is "Bob is the Oil Guy" site.

My preference is manufactured synthetic oil [most any brand] since it is more uniform and has fewer contaminants than refined "dino" oil and typically will perform better with less breakdown in High RPM use. My 04XLR 4.6 Northstar specs Mobil 1 Synthetic so I know that the Caddy engineers proved out this one in performance applications. In my 03 DHS I use Synthetic 5W-30 as well as the rest of my vehicles with no problems. My family drives over 100K per year [ 2 Adults, 2 teenagers] and I get to be the full time mechanic on our 5 vehicles.

Since your car is running fine with no leaks, etc. I would keep away for High mileage oils with additional additives [ contaminants?].

Bob is the oil guy is a great site, but remember that there is a difference between educated guesses and facts.

The guru has made some great posts on that site, including posts about what I am going to tell you right now.

The older Northstars are designed to use with standard of-the-self oil, which includes dino oil.

There is no need to use synthetic oil at all, in for instance, a 1993 STS. The only applications that benefits from using synthetic oils are cars specified to use synthetic/semi-synthetic oils. I.e. cars with turbo, cars without engine-oil coolers or high-performance cars were the oil-cooler would have been even larger with dino-oil.

Sludge for instance was a problem in the 1970's with 10W-40 oils and other oils with large viscosity spans. Sure the dino-oils are more succeptible to heat but that doesn't matter on a car specified for "all oils", especially not on a cooler running car. The oil-cooler makes dino-oil work just as good. The reason that newer Northstar engines are speced with synthetic oil is that the oil-cooler is gone. Lesser possible leak points.

It's quite simple really. Stick to the specs and you will be sure that no harm is done. Be aware though that older Northstars require higher ZDDP levels than the oils of today can deliver.

On the other hand using synthetic oils on a car that doesn't demand it won't hurt anything, BUT there will be no magical earnings/positive effects from using synthetics because the only advantage in using synthetic is a slightly higher temperature breakdown resistance.

[mike27513]

One source for good info on Oils is "Bob is the Oil Guy" site.

My preference is manufactured synthetic oil [most any brand] since it is more uniform and has fewer contaminants than refined "dino" oil and typically will perform better with less breakdown in High RPM use. My 04XLR 4.6 Northstar specs Mobil 1 Synthetic so I know that the Caddy engineers proved out this one in performance applications. In my 03 DHS I use Synthetic 5W-30 as well as the rest of my vehicles with no problems. My family drives over 100K per year [ 2 Adults, 2 teenagers] and I get to be the full time mechanic on our 5 vehicles.

Since your car is running fine with no leaks, etc. I would keep away for High mileage oils with additional additives [ contaminants?].

Bob is the oil guy is a great site, but remember that there is a difference between educated guesses and facts.

The guru has made some great posts on that site, including posts about what I am going to tell you right now.

The older Northstars are designed to use with standard of-the-self oil, which includes dino oil.

There is no need to use synthetic oil at all, in for instance, a 1993 STS. The only applications that benefits from using synthetic oils are cars specified to use synthetic/semi-synthetic oils. I.e. cars with turbo, cars without engine-oil coolers or high-performance cars were the oil-cooler would have been even larger with dino-oil.

Sludge for instance was a problem in the 1970's with 10W-40 oils and other oils with large viscosity spans. Sure the dino-oils are more succeptible to heat but that doesn't matter on a car specified for "all oils", especially not on a cooler running car. The oil-cooler makes dino-oil work just as good. The reason that newer Northstar engines are speced with synthetic oil is that the oil-cooler is gone. Lesser possible leak points.

It's quite simple really. Stick to the specs and you will be sure that no harm is done. Be aware though that older Northstars require higher ZDDP levels than the oils of today can deliver.

On the other hand using synthetic oils on a car that doesn't demand it won't hurt anything, BUT there will be no magical earnings/positive effects from using synthetics because the only advantage in using synthetic is a slightly higher temperature breakdown resistance.

In general, I would agree with you. The exception is my 04 XLR 4.6 N-Star which does specify Mobil One Synthetic 5W-30. This oil is also spec'd for newer Corvette engines with oil coolers. The other comment is that refined Dino oil has inherently higher levels of naturally occurring trace elements [contaminants] as opposed to "manufactured" synthetic oils. In this case the poster says that uses his DTS in high rpm/performance in the Hot South [Texas] environment so I think he might benefit from synthetic. So while I agree synthetic is probably overkill for most applications, I like to have the wide margin to spec limits. Tack sa mycket

[Texas Jim]

In general, I would agree with you. The exception is my 04 XLR 4.6 N-Star which does specify Mobil One Synthetic 5W-30. This oil is also spec'd for newer Corvette engines with oil coolers. The other comment is that refined Dino oil has inherently higher levels of naturally occurring trace elements [contaminants] as opposed to "manufactured" synthetic oils.

In this case the poster says that uses his DTS in high rpm/performance in the Hot South [Texas] environment so I think he might benefit from synthetic.

So while I agree synthetic is probably overkill for most applications, I like to have the wide margin to spec limits. Tack sa mycket

That is true...I also do a good bit of driving in the desert SW.

New Mexico, Arizona and Southern Utah..

I think I will just keep using the synthetic in it.

It has done well so far and I didn't see any reason that anyone put forth in a post to give me reason to change what has worked well so far.

PS:..I was in Raleigh the other day on vacation.

[JohnnyG]

I think you have made a very wise decision. And after you are finished reading up on GF-5, consider this little tidbit that I ran across a few moments ago.

http://www.businessweek.com/ap/financialnews/D9IR0NCO0.htm

There is nowhere to go but up on ethanol content, along with all of its problems!

[Texas Jim]

I think you have made a very wise decision. And after you are finished reading up on GF-5, consider this little tidbit that I ran across a few moments ago.

http://www.businessw...s/D9IR0NCO0.htm

There is nowhere to go but up on ethanol content, along with all of its problems!

JohnnyG,

Thanks for the link.

I had heard something about that on the news earlier.

I don't like it....AT ALL.

My car runs so much better on REAL GAS...when I can find it, (which is very seldom any more) than it does on the 10% ethanol JUNK.

I hate to think what it will be like with 15% or more ethanol.

Not a good thing at all.

I get a 7% to 10% improvement in fuel mileage when I can find "REAL GAS" vs the 10% ethanol junk.

I really wish someone could explain to me how that is saving any crude oil from being refined.

I just don't "GET IT"...reckon I am just too uneducated and dumb to understand it.

Then again, I have a suspicion that it may be a case of "FOLLOW THE MONEY"... I don't know.

[JohnnyG]

My car runs so much better on REAL GAS...when I can find it, (which is very seldom any more) than it does on the 10% ethanol JUNK.

I hate to think what it will be like with 15% or more ethanol.

If you think THAT sucks, and it does...the EPA/Corporate target right now is 20% ethanol! Odd thing though, the article says that 15% is only recommended for cars/trucks newer than 2007, so that leaves you out completely! Just exactly how are the stations going to manage this little trick?

[Texas Jim]

My car runs so much better on REAL GAS...when I can find it, (which is very seldom any more) than it does on the 10% ethanol JUNK.

I hate to think what it will be like with 15% or more ethanol.

If you think THAT sucks, and it does...the EPA/Corporate target right now is 20% ethanol! Odd thing though, the article says that 15% is only recommended for cars/trucks newer than 2007, so that leaves you out completely!

Just exactly how are the stations going to manage this little trick?

I have been wondering the exact same thing.

Either they will have to buy all new pumps with 4 choices or maybe do away with mid grade.

I would think that they will need to provide the "CHOICE" of 10% or 15%, depending on what year model car you have.

As for me, personally, I will "ALWAYS" choose the one that has the least ethanol in it. .. ..

[JimD]

....Then again, I have a suspicion that it may be a case of "FOLLOW THE MONEY"....

When you follow the money you will bump into several groups of well paid ethanol lobbyists inside the beltway over there in dismal swamp land.

One option is to deny this administration a congressional majority on 11/2/2010.

Another option is to make certain this is a one-term administration on 11/6/2012.

The retail merchants association has to be all over this ruling because your local gasoline retailer will be faced with the burden of fronting the money to install yet another storage tank in the ground. Thousands of storage tanks.

Guess who will eventually pay for that!

It all comes down to politics. And politics today is a synonym for.... but I digress. Vote your check book balance. And not the balance today but the balance 5 or 10 or 20 years from today.

[sOAP BOX MODE = OFF]