Question: synthetic oil change intervals

[steve689]

Time wise how long can you go between oil changes? I only drive about 2k a year and hate climbing under that beast. Is it o.k. to go a couple of years with synthetic oils? Car is garaged and I live in the south (no winters).

 

[Hib Halverson]

It depends on the synthetic oil you use and what type of driving you do.

 

[Clive]

My 2 Cents Worth

Well, 2000 miles isn't much at all but I feel that even synthetic oils will hold contaminants.

You probably could get away with a change every 2 years at that rate but engine oils, even synthetics, are cheap compared to possible engine damage and repairs down the road.

If it was my car, I'd still do a full change if I was going to store the car for any length of time or at least once a year. However, living down south with no winters, I don't know why you don't drive it more often.

 

[catbert]

GM requires annual changes regardless of how few miles driven. Or that the OnStar message I got every year when I wasn't putting miles on the Z06.

 

[Hib Halverson]

First of all a post above says oil "holds" contaminants. Clearly there's some misunderstanding about how an engine's lubrication system works.

"Contaminants", ie: solid particles, water, acids are not "held" by the oil. Solids, at least any which are big enough to damage engine parts, are trapped by the oil filter. Water evaporates or "boils off" once oil temperature gets up to normal and the vapor goes out through the PCV system. Acids are neutralized by the engine oil's corrosion inhibiters.

As for change intervals, I'll offer some of my experience over nearly 20 years of using synthetic engine oil and doing spectrographic oil analysis on a regular basis.

On average my Corvettes see limited annual mileage.

I use Red Line 10W30 in all but one and that one gets Red Line 10W40. Each has its oil spectrographically analyzed at each oil change. The analysis looks at wear metals and oil condition (strength of corrosion inhibiters, viscosity, moisture and so forth)

I've run crankcase loads Red Line engine oil as long as five years without an oil change. During that period, I change filters every 3000-5000 miles depending on the size of the filer. In every case of running oil 3-5 years, the spectrographic analysis comes back showing no problems with corrosion inhibiters or viscosity. I've done that with both my C3 Big-Block hot rod, my 95 ZR-1 and my C5. The Big Block, because of piston-to-bore clearance typical of racing BBCs, uses about a qt. every 800-1000 miles. The LT5 and the LS6 uses about qt. about every 6000 miles.

Now...I don't advocate 5 year oil changes for "everyone". I'd only suggest their possibility to those running Red Line Engine Oil in engines which NEVER see short trip duty cycles, are not operated in a dusty environment and which get regular filter changes. Could this be done with other premium synthetics? Perhaps, but I'd want to see some oil analysis data before I'd try it.

Would I suggest this for a Corvette using Mobil 1 5W30?

No.

Could you go 2-3 years using M1 5W30 and changing the filter every 3000 miles?

As long as the duty cycle had NO short trips and the car was not operated in dusty environments, you'd be ok.

 

[NORTY]

Very good post, Hib. The only thing I might change is "acids are controlled by corrosion inhibiters."

Actually, the acids (mostly caused by sulphur in the fuel) are neutralized by the alkalinity (potasium hydroxide) in the oil. (TAN or TBN)

ASTM test # D664 or D974 are used for this.

However, what you say regarding the vehicle's storage environment, it's operating environment, and how it's operated, all need to be considered when "oil life" is being evaluated.

Since the OP's car is driven 2000mi/yr, and it doesn't see freezing temperatures, I'd go 18 months comfortably.

 

[Clive]

Clearing up "Contaminants"

Hi Hib;

When I meant contaminants, I was referring anything that's not supposed to be in the oil. Water (if any) boils off with heat, heavier/larger particles eventually sink to the bottom of the oil pan or are caught by the oil filter when the engine is running. That would leave the acids and anything else not supposed to be there.

My Corvette is the first I've had that uses synthetic oil so I'm used to the "recycled dinosaur" stuff. Like a lot of drivers, I also don't have a clue what additives the oils contain, all I know is that the oil does what it's supposed to do and everything has a life span.

On my other cars, and when I was apprenticing, I was told changing the oils when needed was the cheapest thing one could do to help the engine live a long time. I was applying that theory and what I'd do if it was my car.

One can learn a lot from more experienced/knowledgable folks but I just wanted to clear up my definition of contaminants.

Cheers.

 

[Tuna]

Since my cars are always driven and routinely see 7-10K a year, I didn't have a response for this question.
With Hib's comments, I thought I'd add my 2 cents. I follow Hib's advice on oil changes to a certain degree. Since my Vettes get driven more, I change the oil more.

Every 3500 to 4000 miles, I'm under my Vette changing the filter. I use Mobil 1 10w30 as we rarely see winters cold enough to need 5w30. Every third filter change, I change the oil also. That means 10-12K miles on the oil and 18 months between oil changes.

I did this with my '92 LT1. When it was 11 years old and had 100K miles on it, I had the engine pulled to add HP. The cylinders and bearing surfaces were perfect and showed no wear. The engine was clean as new inside. It went back together with standard sized bearings and rings. It didn't need to be rebuilt but since it was apart for a new cam and heads it got new stuff. I can live with that.

The oil change monitors in my Vettes and CTS seem to want an oil change every 6500 to 7000 miles. I'm doubling that with my Vettes. My Vettes don't do a lot of short cycle work and the oil almost always reaches full operating temperature each time so I don't have to worry about water staying in the oil.

Cars that sit in the garage a lot may need to be treated differently, I'm just not sure how.

 

[mikeCsix]

My perspective on oil changes is to follow the manufacturers recommendations as to type and change interval. I assume if the car is only driven 2000 miles per year, many of those miles may be short duration where engine doesn't get warm enough to drive off the condensation in the oil. If you are running into battery issues, this is another indication you are not driving garage queen far enough on your trips. If there is a period of time the car sits dormant, I would change the oil just before that time and take her for a long drive, enjoy the heck out of it prior to putting her to bed for the season.

For these cars, oil maintenance is pretty cheap. It helps the longevity of the engine, so if you plan to keep it I would do the recommended oil change intervals. I would venture to say GM did some research to come up with their recommendations and the development of the oil monitoring system. With adherence to the recommendations we get a 5yr, 100,000 mile warranty. When I bought my then brand new Yukon Denali in 2006, I was suspicious of the oil monitoring system. I was changing the oil at 50% and it was always pretty clean. After the first few times, I let it go to 90% and made that my target which is what I do with all of my GM cars (my 2008 Z-51, just traded for a '12 Grand Sport, '11 Equinox and aforementioned Denai). The Denali now has 75k on it and runs like new, it should as its a well maintained vehicle. With the oil monitoring system, I trust I get the full use of the oil and I don't have to pay particular attention to the mileage between oil changes. I also tend to keep my cars (except for the '08 Z-51) and look forward to many miles on well maintained vehicles. No slight against the '08 either. Just wanted to upgrade to a new vehicle and really like the GS with its wider tires and bigger brakes. I like to do hpde events and after extensive investigation with brake/wheel/tire/wide-body upgrades, I would be better off buying a new car so I did.

 

[mikeCsix]

P.S. Like Catbert says, On-Star is watching your vehicle maintenance intervals. Pretty convenient for GM if there are any warranty issues and you haven't been changing your oil....

 

[Tuna]

My new Volt says to change the oil every 24 months - unless indicated otherwise. Give that the gas engine in the Volt doesn't run very often in intended use, that all GM figures it needs.

 

[Hib Halverson]

I think you have to change the electrons in the electric motor windings every 36 months.

Also...recharge the fire extinguisher every 24 mo.

 

[Tuna]

I think you have to change the electrons in the electric motor windings every 36 months.

Also...recharge the fire extinguisher every 24 mo.

I'm still checking on this!

I reminded my co-workers not to park too close unless they want they car burned down. I usually get plenty of room around it that way. otfl

 

[Tony1Leo]

For MikeCsix,
The oil monitoring system doesn't measure the oil viscosity as it claims. I believe it just counts the mileage and maybe basic driving habits. After a few oil changes came out pretty clean, I just reset my oil monitoring system to 99% without an oil change. It reset and just moved down in percentage as it normally does. I got nervous and changed the oil after about 3000 miles. The oil monitoring system showed about 60% at this point. So why would it tell me it's time to change the oil, but let it reset back to 99%. My thinking was that the computer would let it reset, but it would rapidly drop back down and tell me I needed an oil change within a short amount of miles. It didn't. It just started counting down again.

I'm still checking on this!

I reminded my co-workers not to park too close unless they want they car burned down. I usually get plenty of room around it that way. otfl

 

[Hib Halverson]

The GM Oil Life Monitor records only two types of data:
1) Number of engine revolutions since last reset
2) Oil temperature history since last reset.

It can't read oil viscosity, oil color, level of contaminants, driving habits or anything else.

The computer does not reset the OLM. It has to be reset manually each time an oil change occurs.

 

[motorman]

there are articles from Mobil about Mobil 1 running 250,000 miles with no oil changes except filters.