Synthetic oil change


#1

Because I telecommute, I put on only 3000 mi. during the last year since I changed the BMW synthetic oil. How long can I go time-wise before I need to change it again, or must I still change it annually?. My car has only 30,000 mi.


#2

I suggest you follow the recommendations in the owner’s manual. There is usually a recommendation such as “XX,000 miles or XX months, whichever comes first.” The part you need to pay attention to is “whichever comes first.” I change the oil in my low-annual-mileage car once a year, regardless of mileage. Sometimes it’s less than 3K.

If your BMW has an computerized oil monitoring system, change it when the computer tells you to.


#3

I believe in BMW its once per year or every 15000 miles.Your due.

Oil breaks down.


#4

Oil does not break down after only 3000 miles or after some specified amount of time – especially not synthetic oil. It breaks down due to actual use.

If you only ever make very short trips, then you should change the oil at the time interval suggested in the manual. Very short trips don’t allow the engine to heat up enough or for long enough to force condensed moisture out of the engine (and oil). Therefore changing the oil on a fixed time interval will help eliminate the contamination.

If you use your car only occasionally but run it for long enough to actually reach full operating temperature for 20-30 minutes when you do, then replace the oil after around 5000 miles, ignoring the time interval. Running the car at full operating temperature for an extended time every once in a while allows the engine to heat for long enough to purge the accumulated moisture.

According to independent tests, modern standard oils will actually last more than 10,000 miles without significant thermal breakdown under normal driving conditions. Synthetics last more than 15,000 miles.

However, I would be hesitant to run more than around 7500-8000 miles without an oil change because the oil filter is unlikely to work efficiently or at all beyond that. If it were possible to change the filter on my car independently of the oil I might be willing to run synthetic oil for 15,000 with a filter change at 7500, but due to the design of my engine I lose a significant amount of oil changing the filter anyway. So I change the oil and filter at around 7500 miles each time. My last car was still running smoothly at 224,000 miles when I traded it in, so it’s a sound strategy.

But for you, I’d suggest changing according to either time or 5000 mile intervals described above, depending on the nature of the driving you do.

Hope this helps.

Russ


#5

Thanks. That was the most helpful answer that I have heard.


#6

I would like to add that even tho the oil doesn’t break down, the oil still attractes contaminants from the surrounding enviroment. Consider this: Just how much money did that last oil change cost? How much does serious engine repair on a BMW cost? And, how much does the car mean to you? An oil change is cheap insurance, so why even bother with asking the question to save a few bucks. Treat your sweet ride, and change the oil once a year like the manual says. Is it really such a hassle?


#7

Oil cannot “attract contaminants from the environment” unless the engine is actually running, and contaminants are being pulled into it. Just sitting unused in the driveway there’s no way for that to happen.

Just how much money did that last oil change cost? How much does serious engine repair on a BMW cost?
This is a straw-man argument. You’re implying that changing the oil at longer intervals will result in a serious engine repair, when nothing could be further from the truth. When have you ever heard of somebody who required any engine repair because they changed their oil less often than once every 3000 miles? How about less often than 5000 or even 7500 miles? My uncle is a mechanic, and hasn’t had to do a “serious engine repair” in the past 20 years that didn’t have a specific, traceable cause… and that cause is never that somebody who does regular oil changes at least every 10,000 miles didn’t change their oil frequently enough.

I too would recommend an oil change according to the schedule in the manual unless some very specific conditions make that unnecessary, as I outlined in my previous answer. More frequent oil changes certainly can’t hurt anything, but implying that less frequent changes will result in “serious engine repairs” is oil company FUD.

Russ


#8

Well Gollee
sounds like simple logic to me
me daddy always said “RATHER BE SAFE THAN SORRY”


#9

If you use a true synthetic, which means Mobil 1, you can change it at 10,000 miles or 15,000 if you use the extended mileage type. No worries.


#10

The big question is how did you accumulate the 3000 miles last year? Did you make a lot of real short trips or a few longer ones?

Most of the damage to oil occurs right after a hot engine is shut down. The oil stops flowing because the pump has been shut off. Most of the oil drains back to the pan, but a little oil is left as a film on all the internal parts, which are very hot and will cook that remaining film.

Every time you shut down, a little more oil gets cooked and eventually, the oil reaches the point where it should be changed. Now some oil also breaks down while the engine is running, but the majority is done while the engine is cooling down

If you made only a few long trips during the year, you can put off the oil change. I have a truck that I only drive about once a week, so I change the oil about every two years or so, synthetic oil. If I drove it every day, I would never go past 6 months, no matter the miles. Short trips in city traffic will take its toll, but that also means a lot of hot shutdowns.


#11

[/quote] If I drove it every day, I would never go past 6 months, no matter the miles. Short trips in city traffic will take its toll, but that also means a lot of hot shutdowns.[quote]

That’s good advice, my wife has a car that usually only drives about 5 miles per day to work. I try to take it out for longer trips every week or two and change the oil about every 6 months, regardless of mileage. Oil changes are cheap, I can change the oil for less than $50, a replacement engine is closer to $5000.


#12

Hello; I’m new to this message board so I’m not sure how this works. I have a '95 Eldorado that has a ‘slight’ oil leak, as the mechanic said, which he will watch. (He may be ready for a new boat.) I saw recently about Max Life oil for older cars. Is this a viable option for mine at my next oil change? Or should I just go forward and trust the mechanic? I’m new to the area and this is the Cadillac dealer. My car only has 76,000 miles and has never given me any major problems after the warranty ran out. Thanks for any advice/comments.
LilyBee


#13

Hi, I can’t throw stones at you since my screen only has reply options to the replies and not to the original post.

With regard to the general idea of when to change oil, I remember the caller whose oil pan was overflowing with water, apparently from condensation. I wonder how long it takes for the water to settle to the bottom of the pan after shutting off the engine. The oil plug is supposed to be removed immediately, so water may not come out first if it is not on the bottom of the pan yet.

Also, what about frothy oil due to moisture content? Will water always indicate itself as some froth? I change my oil at most once every two years and have never noticed any water. I drive only a few miles round trip to the local produce market, and it has been quite a while since I recall the electric radiator cooling fan running. I have gotten my driving down to a little over 200 miles per year.

The key seems to be that for each car or situation, the needs may vary. I may have done my last oil change on this car last summer.


#14

PS. I use synthetic oil, too. changing the oil is enough of a pain to warrant it, I think.


#15

Re: “Better safe than sorry.”

The problem is defining “safe.” Unchecked, that logic would dictate oil changes every 1000 miles. “Better safe than sorry.” Or every 500 miles. That’s even safer, right?

I’m saying that based on experience (mine and my uncle’s) and actual test results I’ve read, 7500 miles is more than “safe” under the vast majority of driving conditions. I outlined exceptions in my previous replies.

Russ