to change or not to change (oil)

[maybe2fast]

so the Lumina is due for an oil change (3000mi), I used synthetic blend oil and a good oil filter, I decided to check the oil first before I dumped the oil, the oil is very clean still, still that clean brown color. not even close to black...what to do!

[sl3196]

Well I'm switching to syn. this oil change and I plan on running it to around 7,000 miles. I'm going to change the filter at 3,000 and top off the oil. If that helps at all.

[Guest TurboSedan]

if it still looks good i would probably wait until 5000 miles. i don't think i'd go over that though. if anything, change your oil filter.

[paulo57509]

so the Lumina is due for an oil change (3000mi), I used synthetic blend oil and a good oil filter, I decided to check the oil first before I dumped the oil, the oil is very clean still, still that clean brown color. not even close to black...what to do!

 

http://theoildrop.server101.com/whatisoilanalysis.htm

[pitzel]

The efficacy of a 3000 mile oil change is just an urban myth intended by oil manufacturers to sell more oil and to wear out people's engines more quickly.

 

If you carefully examine the used oil analysis section of bobistheoilguy.com, it is fairly clear that oil needs some time to 'break-in' before it delivers the optimum wear protection. Changing oil at 3000 miles does not allow this 'break-in' process to properly occur, thus the oil is actually promoting more wear than it would be if you changed it at a more reasonable interval, say, 5000 or 7500 miles, as specified in the owners manual.

 

Also, when you pour brand new oil into the crankcase, it has some more volatile components that get boiled off. Where do these volatile components end up? Right inside your engine, through the PCV and crankcase breather systems, and past the rings, where volatile components are partially burned and lead to O2 sensor contamination, among other things. Many off-the-shelf oils contain volatile substances that aren't good for catalytic converters either -- so when you change oil more often, more and more of this crap ends up in your expensive components than would with a normal oil change interval.

 

Some of this effect is attributed to the oil itself, and some to the filter. It has been said that oil filters, much like K&N's, actually require some dirt in them to operate at their peak efficiency. Changing oil and filter prematurely at 3000 miles doesn't allow this process to take place, much like washing a K&N every month doesn't allow for optimal filtration to take place.

 

Essentially with wear, you can plot a 'U'-shaped curve, where wear with new oil is relatively high, because of the oil 'breaking in', and wear levelling out at its minimum after roughly 3000-5000 miles of operation. Then after approximately 8000-10,000 miles on the same oil, the oil starts to promote increased rates of wear, hence the recommendation for a 7500 mile oil change. Go study bobistheoilguy.com, changing oil too often is bad for your engine, bad for your PCV and emmissions controls, and very wasteful on your pocketbook, not to mention the environment.

[Dannymik]

The efficacy of a 3000 mile oil change is just an urban myth intended by oil manufacturers to sell more oil and to wear out people's engines more quickly.

 

If you carefully examine the used oil analysis section of bobistheoilguy.com, it is fairly clear that oil needs some time to 'break-in' before it delivers the optimum wear protection. Changing oil at 3000 miles does not allow this 'break-in' process to properly occur, thus the oil is actually promoting more wear than it would be if you changed it at a more reasonable interval, say, 5000 or 7500 miles, as specified in the owners manual.

 

Also, when you pour brand new oil into the crankcase, it has some more volatile components that get boiled off. Where do these volatile components end up? Right inside your engine, through the PCV and crankcase breather systems, and past the rings, where volatile components are partially burned and lead to O2 sensor contamination, among other things. Many off-the-shelf oils contain volatile substances that aren't good for catalytic converters either -- so when you change oil more often, more and more of this crap ends up in your expensive components than would with a normal oil change interval.

 

Some of this effect is attributed to the oil itself, and some to the filter. It has been said that oil filters, much like K&N's, actually require some dirt in them to operate at their peak efficiency. Changing oil and filter prematurely at 3000 miles doesn't allow this process to take place, much like washing a K&N every month doesn't allow for optimal filtration to take place.

 

Essentially with wear, you can plot a 'U'-shaped curve, where wear with new oil is relatively high, because of the oil 'breaking in', and wear levelling out at its minimum after roughly 3000-5000 miles of operation. Then after approximately 8000-10,000 miles on the same oil, the oil starts to promote increased rates of wear, hence the recommendation for a 7500 mile oil change. Go study bobistheoilguy.com, changing oil too often is bad for your engine, bad for your PCV and emmissions controls, and very wasteful on your pocketbook, not to mention the environment.

 

 

Thanks for a different look at this. I've never heard anyone say any of that which is why I'm going to look into this. I guess I can switch my ways for the right reason especially since Mobile One is not cheap.

[pitzel]

Thanks for a different look at this. I've never heard anyone say any of that which is why I'm going to look into this. I guess I can switch my ways for the right reason especially since Mobile One is not cheap.

 

Definitely. Keep a very close eye on the coolant though. I've been told the 3100/3400 with Dex-Cool in the Grand Prix is a disaster waiting to happen in terms of the intake gaskets. Over 7000 signatures from Dex-Cool filled 3100s/3400s at http://www.gm-v6lemons.com tells ya something, eh?

 

Seriously though, if I were you, I would look into procuring the updated gasket set and the tools to do the gasket changeout. And spend the $20 to have your oil analyzed to see if the coolant ingress has already started to affect your engine. That is, unless you were fortunate enough to have spent the extra money on the L67 (3800-2-Supercharged)

[Dannymik]

I have the series 2 3800 L36...no 3100/3400 in her

[Mizouse]

Thank god, someone else finally realizes that oil does not have to be changed every 3000 miles. I have been telling people this for years and they just laugh at me and tell me I am damaging my engine. Glad to see some kind of proof on this.

[pitzel]

Thank god, someone else finally realizes that oil does not have to be changed every 3000 miles. I have been telling people this for years and they just laugh at me and tell me I am damaging my engine. Glad to see some kind of proof on this.

 

Brand new Chevy Corvettes say change Mobil-1 every 15,000 miles. And surely a Corvette, with its additional cylinders, and more aggressive drivers, would be harder on oil. And yes, they specifically specify Mobil-1, not because other synthetic oils aren't just as good, but rather, because its available in nearly every auto parts store and Wal-Mart in North America.

 

I've seen a UOA on the Internet somewhere where an individual ran a 3.1L V6-powered early 90s Lumina some 34,000 some odd miles on a certain synthetic oil, without changing it, and it still tested out to be within spec in used oil analysis. If you can keep the coolant out of these engines, the oil should pretty much last forever.

 

There's a gentleman around here who runs a fleet of 2002 or 2003 Pontiac Montana minivans with Mobil1 5W-30 and he uses UOA (used oil analysis). The oil is consistently running 40,000-50,000km's before it goes out of spec, and even then, its only suffering some viscosity thickening (bad for fuel efficiency), not actual breakdown. But personally I'm not that brave

[SigEpCutlass]

that may be all well and good, but i prefer to keep my car at peak efficiency at all times. I stick to all reccomended maintenance schedules. With synthetic oil, it is generally changed every 7,500 miles and you change the filter every 6 months. That's what my family has been doing for ages with amsoil. In all of our vehicles, we use amsoil 0w-30 Series 2000 Racing Oil. It's expensive, but it's great. I'll post a graph on it if anyone's interested.

 

For practical purposes, those vehicles are:

-'92 SHO

-'94 Cutty (mine)

-'00 VW Golf

-'00 Subaru Outback

 

My car is the only one that doesn't have a MTX...

 

I figure...maintenance schedules are made for a reason...to keep your car running correctly. Maybe I don't believe in this huge dealer conspiracy because I do almost all my work on my car myself...

[pitzel]

that may be all well and good, but i prefer to keep my car at peak efficiency at all times. I stick to all reccomended maintenance schedules. With synthetic oil, it is generally changed every 7,500 miles and you change the filter every 6 months. That's what my family has been doing for ages with amsoil. In all of our vehicles, we use amsoil 0w-30 Series 2000 Racing Oil. It's expensive, but it's great. I'll post a graph on it if anyone's interested.

 

 

I'm not questioning your practices -- they seem to have served you well. However, when the 7500 mile oil change recommendation was made in the manuals of our cars, this was done in the late 80s when group I dewaxed oils were the only oils available commonly on the market, with synthetics occupying an obscure niche reserved for turbo'ed eurotrash cars.

 

Chevron et al commercialized hydroisomerization/hydrotreating/hydrocracking for motor oil in 1992 or 1993, which led to higher quality and very commonly available (50% of the world's supply) group II oils, and now polyalphaolefin (PAO) group IV oils are becoming very inexpensive due to the new natural gas to liquids facilities that have come onstream in both the middle east, Russia, and in Alberta, Canada.

 

So the oils today are far better than the stuff most people were using when they bought their cars, and fuel standards have been upgraded as well, especially with the sulfur standards brought in under the Clean Air Act in the late 80s/early-mid 90s. I'm of the opinion that with all these developments, that the owners manuals recommendation of 7500 miles is somewhat obsolete. But at least you aren't suffering the excess wear phenomena that is the result of the 3000 mile oil change.

[maybe2fast]

I am going to give it another grand and check it

[ismellrealbad]

Definitely. Keep a very close eye on the coolant though. I've been told the 3100/3400 with Dex-Cool in the Grand Prix is a disaster waiting to happen in terms of the intake gaskets. Over 7000 signatures from Dex-Cool filled 3100s/3400s at http://www.gm-v6lemons.com tells ya something, eh?

 

jeeze i read that site and my jaw almost dropped....i cant believe that many people went through the same nightmares i did

[THe_DeTAiL3R]

I would leave the oil for now but maybe change the filter soon.. 1k should be fine

[HokemBokem]

I just changed my oil today and I was at exacly 3000 miles since my last oil change. I dont run synthetic or expensive oil filters so I think I will continue to change it every 3000-3500 miles.

[Brian P]

not to be ignorant but I couldn't find anything on bobistheoilguy about oil changes at 3k being worse for the engine. Where is that?

[HokemBokem]

not to be ignorant but I couldn't find anything on bobistheoilguy about oil changes at 3k being worse for the engine. Where is that?

 

Yea wouldent it be better for the engine if you changed to oil often?

[slick]

I do mine between 5,000 and 7,000 miles (fully synthetic too, with about 17,000 miles on this engine/tranny combo).

[pitzel]

not to be ignorant but I couldn't find anything on bobistheoilguy about oil changes at 3k being worse for the engine. Where is that?

 

Yea wouldent it be better for the engine if you changed to oil often?

 

I will dig up some of the UOA's that indicate this trend (to satisfy Brian P's curiosity), but the key thing to keep in mind is that you need to compare wear rates per mile (or per 1000 miles). Sure, oil is going to come out of the car looking uglier at 10,000 miles than it will at 3000 miles, but the overall wear, if you're using a good synthetic, will be less.

 

As I wrote earlier, with the modern synthetics, they seem to perform the best once they've been 'broken in'. Yes, a break-in period for oil. Gives the oil the chance to have some of the extraneous junk 'boiled off', and for the filter to collect enough 'dirt' to render it more effective. Also gives the oil some exposure to the bearings, where the bearings have the opportunity to pulverize (shear) the oil molecules, thus making them more uniform and suitable for lubrication.

 

Oil that is dark isn't necessarily a bad thing -- in fact, darker oil is a 'good' thing because it means that the oil's detergent additives are doing their job. If dark oil was 'bad', then no diesel engine on earth would run for more than a few months from the manufacturer since diesels darken their oil almost immediately. Truth is, diesel engines have exceptional reliability, despite how dark/dirty they make the oil quickly, and the diesel engine environment, with its high compression ratios, high soot loading, and high sulfur fuels, is undoubtedely more demanding.

 

Will have links to relevant UOA's tomorrow. g'night.

[Brian P]

Cool. So we're talking about long oil change intervals with synthetics then. Not conventional oil. Looking forward to seeing the scripts otherwise.

[HokemBokem]

Well i dont use synthetic so I would still have to change it at 3,000 miles right?

[buckethead]

Holy crap Pitzel, did you minor in lubrication sciences or something? J/K

 

 

Anyways, this is what I've heard about oil changes. If you are using a non-synthetic oil and generic filter, change your oil between 3,000 and 5,000 miles depending on the type of driving you are doing... For example more city driving with stop and go traffic puts more strain on your engine which will break down oil much faster. If you do more highway driving (or you drive like my grandmother) there's no reason your oil shouldn't last you at least 5,000 miles before a change is required.

 

Synthetic oils resist breakdown much much better than non-synthetics, therefore they will last well beyond 5,000 miles before a change is required. I've heard anywhere between 7,500 and 12,000 miles, depending on the type of driving you do. These numbers may be less if you are switching to a synthetic on a high mileage engine. Blowby will cause gas contamination in your oil and therefore break it down sooner. Other than that I agree with Pitzel, It's not necessary or even a good idea to change synthetic oil every 3,000 miles. You'll be better off waiting untill about 7,000 miles or more, even if just for cost savings.

 

Change your filter when you change your oil, If your oil will last 7,500 - 12,000 miles then the filter will too. In fact, if you're using non-synthetics with a quality filter, you could get away with changing your filter every other oil change. But don't try to change the filter and keep the same oil. You'd end up making a mess trying to change the filter without taking all the oil out first anyways.

[jeremy]

I would keep using it for another couple thousand miles...

[GnatGoSplat]

Well i dont use synthetic so I would still have to change it at 3,000 miles right?

 

No, up to around 5,000 should be fine.

I've always changed my oil according to the oil life monitor which varies between 4000-6000 and I've never had an oil-related problem.