oil change interval

Factual Questions
1

My VW is dead. Just 2 days ago the oil light came on. I was scheduled for oil change in April so I thought I’d add a quart til Monday. When the light stayed on I put in another quart (yes I’m stupid, no I didn’t check the stick). So later on Sunday I barely made it home. The engine lost power, light came on, and it got really loud. CHecked the oil and it was over the mark.

Had to have it towed to the VW place where they drained the excess and told me the engine was completely unsalvageable, mired in thick tar and goo and suggested that the oil had never been changed. Well I’ve had the oil changed with synthetic put in 3 times: at 6,000 miles, at 19,000 miles, then at 36,000 miles (during that last stretch I added regular oil after asking if it was okay to mix)- I got the printout from the Jiffy Lube. So now at 46,000 miles I need a new engine.

Now everyone is blaming everyone else and now me (for going too long between oil changes). I was trying to go every 6 months because I thought that was way better than the 0 times I had the oil changed in my Subaru over 4 years…Every one I’ve talked to says change it every 3,000 miles with regular and every 5 - 7,000 miles on synth. I’m skeptical about the interval everyone keeps spouting off as if it were god’s law- they sound like they just say this because they’ve always heard it. So my question is, is there really any proof about the 3000 mile thing? And what about the synthetic oil? I think it’s either something defective with the vehicle or the oil (that in my opinion shouldn’t gunk up like that). Obviously I don’t want to hear it’s my fault, but somehow it’ll come down to that :slight_smile:

Any information on the interval or synth in general is much appreciated.

2

17,000 miles between one change? Wow, that’s got to be a record, if I ever saw one, although I think my sister might have the one beat.

Yeah, we discuss this on the board a lot only thing is you can’t search for three letter words like ‘oil’ to find it. But most agreed, I think, that 3000 was too often & about 5000 is about right depending on your car, of course. My 65 vw bug I would do it every 3000 miles.But that was in the 70s.

3

Newer cars can go 5,000 mi. in between, 5,500 pushing it. Older cars should go more frequently. With older cars, every now and then (once every 3-5 years maybe), get an oil change, drive it around for a week, then change the oil again. It should drastically slow the oil gunking up, as this is a way of cleaning the engine. This may seem excessive, but $25 for an extra oil change beats the hell out of $2-3000 for a new engine.

4

The first thing that should probably be pointed out is that the “oil light” on all cars I’m familiar with indicates low oil pressure, not low oil level: the two don’t necessarily go together. I’m not a mechanic (and there are some very well-qualified ones on this board), but it sounds like the oil pump, or maybe the filter, got so gummed up by the old oil and the crap in it that the engine was starved for oil despite having a lot in there. I’ll be corrected soon enough if I’m off base, I’m sure.

As far as the change interval, opinions vary.

Many hold on to 3,000 miles like gospel and usually reply with, “It’s cheap insurance,” when questioned about it. There have been studies that suggest that this is too often, but reasonable people can differ on this, I think.

Modern cars’ owners manuals typically (IME) specify somewhere between 5,000 and 7,500 miles for “normal” usage. The “severe” usage recommendation is usually quite a bit less - 3-4,000 miles. Owners are advised to read the definition of “severe use” in their particular manual carefully, as more vehicles qualify that one might think.

My 1997 Mazda B2300 pickup calls for 5,000 in regular use and 3,000 in severe. My wife’s 2000 Honda Civic’s numbers are 7,500 and 3,750, respectively.

17,000 miles is surely too long, by a lot, for almost any vehicle.

You don’t give the model and year, but since it’s only got 46,000 miles on it I’m guessing it’s only around five years old? Do you have the owner’s manual? What does it recommend?

5

Well, it’s a 2001 Passat wagon. I guess my point is, I drove a mustang for years and a Subaru for years and never changed the oil and only sometimes added it. (My husband took them a couple times at most to change the oil). I drive quite a bit now as I did then, and I guess I just have a hard time believing that suddenly changing the oil is such a big thing…Owner’s manual says 5 I think. Jiffy Lube told me I could go 6 months between oil changes with the synthetic (I didn’t hear anything about miles)…

6

I drive a 2000 Olds Bravada. It recommends 3k miles for severe duty, which can be driving in areas with extreme climates, areas with lots of sand, mud, and a lot of city driving. It also says for normal duty its ok for 5k intervals. I get my oil changed every 3k miles.

7

I’m guessing the problem with the VW isn’t that you went 17,000 miles without an oil change but the fact that you added two quarts when you probably didn’t need to add any. The oil light was likely an oil change light, not an oil level or oil pressure light. Driving around with two extra quarts of oil is what killed it.

I know people that have driven over 100,000 miles on a car and have never once changed it. I personally think it’s crazy, but it’s entirely within the realm of possibility.

I use Amsoil, one of the best synthetics, and change it every 7,000. The recommended interval with Amsoil is 25,000 miles, with filter changes every 10-15,000.

8

Well, this has me wondering if the trashing of the engine was directly related to the long oil change interval or not.

When the oil light comes on, this is because the oil pressure sending unit (mounted somewhere on the engine) is registering low oil pressure. IOW, the engine is for some reason not getting adequate oil circulation and thus isn’t being adequately lubricated. Continuing to run an engine in this state will generally lead to its rapid demise.

I believe a horrifically low oil level will cause low (well, zero) oil pressure, but that doesn’t seem to have been the cause here - the level was fine, or at least close enough.

This raises (to me) the possibility of the oil pump having failed. Did the shop say anything about that? If that happens, even if the oil was changed the day before, the engine is not long for this earth if one continues to drive it.

If it’s the pump that failed, was it caused by the old, dirty oil? Maybe. I’ll defer to the experts on that.

Leaving aside the long interval since the last oil change, I’d say that the fatal mistake was likely your continuing to drive the car with the oil light on. As a general rule, the red (as opposed to amber) warning lights on the dash indicate that something needs attention NOW, and that continuing to drive is either dangerous or destructive.

Reading Severian’s post on preview, he brings up a good point. Can you describe the warning light that came on more specifically? What color was it? Can you check your owner’s manual to see for sure what that light represents?

I’d be very surprised if the “low oil pressure” light and the “change oil soon” light were the same, but I’ve never owned or worked on a car that had a change oil light.

9

The light is a red oil can to the side and big red letters that say “STOP” (flashing) then “Refer to Manual” then “STOP ENGINE NOW” then loud beeps then repeat. Needless to say, I stopped within 2 miles and put oil in because, in my little head I figured that’s what you do when the oil light comes on. I mean, what else does one DO with oil besides ADD it? Like I said, I know now it was stupid (I’m learning fast though if too late)

10

Well, I guess I was wrong; it sure wasn’t a change oil indicator.

11

I agree that 17,000 miles without an oil change, while painful to think about, shouldn’t of itself kill an engine. I’m curious how adding oil above the “full” level would do so.

The OP mentioned that the engine was found to be “mired in thick tar and goo.” This sounds more like a symptom of neglect than of overfilling.

12

It even mentions Volkswagens.

13

Mistake. When it says “STOP ENGINE NOW”, it means **NOW/b], not 1 or 2 miles from now.

…and put oil in because, in my little head I figured that’s what you do when the oil light comes on. I mean, what else does one DO with oil besides ADD it?

One checks it. If it’s low, you top it up to the correct level, then start the engine and see if the light goes out and stays out. If it does, you’re likely OK. If the light doesn’t go out within about 10 seconds, or if it wasn’t low in the first place, you shut the engine off and have the car towed to a repair shop for investigation.

I know no one reads their owner’s manuals, but I’ll bet that’s exactly what it instructs you to do.

14

YMMV, of course, but some things to ponder about oil change intervals.

  1. My BMW has synthetic oil, and it has a 15,000 mile change interval. I’ve never had a problem with it. I’ve asked the service manager about this, and he said he never saw a problem due to this interval either. Let’s face it… I don’t think they’d do something that would negatively impact these cars without being confident that the oil change interval was fine. They have a stellar reputation for producing a high performance vehicle. I doubt they’d risk their reputation over something as simple and cheap as an oil change.

  2. I owned a 67 Mercury, and the manual stated that you should change the oil every 6,000 miles and the filter every 12,000 miles.

  3. Most new cars suggest a 5,000 interval.

  4. As someone mentioned already, 3,000 has been drilled into our heads by slick marketing campaigns. The beauty of this is that changing your oil more often will certainly not hurt your car, and it is a relatively cheap insurance policy. Oil companies love the fact that instead of 5 or 6 thousand miles, 3 thousand is now the norm. That doesn’t hurt the old bottom line. Obviously, 17,000 miles is pushing it (especially if you weren’t using synthetic), but I don’t think anyone’s engine life would be significantly reduced by changing the oil and filter every 5,000 miles instead of 3,000… especially if the vehicle’s manufacturer recommends it. Of course, I could be wrong. Are there any studies out there to back up the 3,000 vs. 5,000 oil change interval (and how long their engines live)?

  5. My neighbor (who is a friend of my father’s) told me that he NEVER changes the oil in his cars. Every 3-5,000 miles, he changes the filter and adds enough oil to top off the engine (around a quart). I asked my father about this, and he confirms that as long as he’s known the man, this is how he’s done it. He’s actually seen him do it. Personally, I wouldn’t recommend this method, but it seems to work for him. (of course, he could be pulling our collective legs, but for 45 years?)

15

And says that excess oil can lead to foaming, which reduces the effectiveness of an oil pump. Makes sense, and could apply to the case in question here. I’d think this would have to have been going on for some time to produce “thick tar and goo.”

16

I don’t see how you can get that much sludge without water or a lot of dirt in the oil. I know that synthetic is supposed to be thoroughly compatible with regular motor oil these days, but if the synth. and the oil are cheap enough, might it be a compatibility problem?

17

Consumer’s Union did a test a few years ago where they used a fleet of NYC taxi cabs, figuring that that’d be pretty close to the harshest driving conditions the average person would put their car through (constant use, lots of short trips, stops and starts, and those velvety-smooth NY roads :slight_smile: ). They monitored oil usage and engine wear very carefully, you can read all the details in a back issue.

End result that they came up with is that 6000 miles is fine even under those conditions. The recent owner’s manuals that I’ve looked at (my old Celica, my folks 90s-era Camry and my new F150) all recommend an interval of about 5000 miles. The oil shops keep slapping stickers on the windshield reminding me to change in 3000 miles but I’ll go with what the manufacturer suggests. Per Click & Clack and a couple of other mechanics, I’ve heard that synthetic oils and certain cars (like recent BMWs) can go far longer in between changes.

Said far too often but particularly true in this case:

  1. YMMV

  2. RTFM

Smooth runnings!

18

If you put too much oil in a crankcase it will create air bubbles and can mess up your valves and lifters. I’m not an expert on cars but my first question would’ve been:

What was the oil level when the light came on? Was it high or low?

If you lost your oil pressure it would likely indicate a blown seal or gasket, etc.

High oil level, you probably wrecked the upper cylinder heads, valves and lifters.

I agree with the others who already pointed out that $20 or $25 every 5,000 miles is a small price to pay for peace of mind. I have a van with over 100,000 miles on it. It purrs like a kitten and never burns oil. I believe fresh oil extends the life of any engine. Synthetic oils are fine too but don’t provide any more protection against friction than regular oil in a maintained engine.

19

The difference is that these cars are driven mostly at opperating tempatures. If these cabs were used for short trips and shut off and allowed to cool down inbetween I would say that would be harsher.

An IC engine is designed to run, not to sit, most wear is done on startup, also most incomplete combustion, most blowby since the rings are not perfect seals and oil will drain while the engine sits.

I do the 3 month oil change, sometimes its 2000 miles sometimes 6000. It’s just easer for me then millage.

20

NOT a good idea! The fact is that oil does wear out. It looses its viscosity. Synthetic oils don’t lose their viscosity as quickly as regular oil. However, all oil gets dirty over time although the filter will remove most harmful particles.

When Mobile1 first came out it was marketed as being good for 25,000 miles. It would hold its viscosity for that long but the problem was that it would get dirty and people wouldn’t change the filter during the interval resulting in engine problems. Mobil1 backed off the claim.

Modern engines operating properly have such close tolerances that they don’t consume much oil. If you just top off the oil and change the filter, over time you will be using oil with insufficient lubricating properties and engine wear will accellerate. Of course, when you change the filter you typically lose about a quart of oil so yes, the overall quality of the oil may be good enought to keep the engine running but it is probably nowhere near good enough to prevent engine wear. Your neighbor probably trades in the car before the problems appear and sticks someone else with the
problem.