Another Oil Change Question
 

I read all the post about changing oil anyware from 3000 to 10000 or more miles. I have 2 MBs, one 91 300D and an 84 500SEL. The 300D is a daily driver which is usually driven 3 miles per day. Possibly 10 miles on the weekend. Total of around 1500-2000 miles/year. The 500SEL is only driven on longer trips but will only get about 2000 - 3000 miles per year. Mobil 1 15W-40 in both cars. How often would you change the oil in these cars. I usually change them at 1500 miles but have been told (on this Forum) that this is crazy. Comments please.

The short trips are worse on the oil than long extended drives. But I would have to agree that 1500 miles is crazy.

If you really...really want to know how long you can extend your oil change you have to get a sample tested. Be sure to get a TBN test. That is the only way to tell how much additives are left in the oil. The other test is only a wear test.

You can get testing done here.
http://www.blackstone-labs.com/

Danny

Agreed on the Blackstone Labs test. I had 4000 miles on my non-sythetic Mobil Delvac 1300 Super and the amount of additives left was a 9 on their scale, with new oil having a rating of 11 so I still had plenty of life in that oil. The amount of soot was around a half percent so I was good there. Most of my driving is highway, putting around 350 miles a week on the car with it being at operating temp for at least a half hour at a time. I wouldn't want to do anything over 3K with the mileage you put on in a year, and all the stop and go.

sailor, how were you able to determine the soot content of your oil? When I sent my sample off to Blackstone, it didn't show a soot percentage.

Sailor,

Your data indicates you could probably run 10-15k miles on dino diesel oil with only 0.5% soot in 4 kmiles. TBN is still very strong.

Why do we still hear the insanity of "Change it hot and change it often". Do they all own stock in Exxon Mobil?:D

240Joe

this is a troll thread, right?

tom w

Yes, for the car that only gets driven 3 miles per day, changing oil every 1,500 miles IS crazy! It should be changed MUCH MORE OFTEN!

Driving a car 3 miles gives the oil no chance at all to heat up and boil out the moisture. Additionally, acid build up is a serious problem.

On both of these cars, oil change intervals should NOT be determined by watching the odometer! They should be determined by watching a calendar. Change oil in them every 3 months, and under NO circumstances let it go past 6 months. It also would be very helpful to run the car to operating temperature and even another 15 or 20 miles AFTER operating temperature just before draining the oil. I am not talking about the temp gauge in the instrument panel reaching it's normal temp. On the average it takes about 17 miles for the oil to reach operating temperature.

Good luck,

Thanks Larry. Thats exactly what I was thinking. I am going to change my scheduel to every 3 months OR every 3000 miles, which ever comes first. Then I am going to save the old oil and sell it EBay as "slightly used Mobil 1 for $5.00 per quart". I'm sure the ones that think I am crazy will love to get it. I may actually GIVE it to them if they pay the postage.
The worst thing you can do to a car is let it sit. Second worst thing is start it and not worm it up completly as you say.

With M1 synthetic, I would probably go 5000 miles/6 months instead of 3000 miles/3 months, but I agree with the principle. Oil is cheap, engines are expensive; when in doubt, change the oil. (I'm about to change mine for the second time within a month after two round trips from CO to MI.)

Besides, if it drives 240Joe nuts, it has to be worth doing! :D :D

Probably a short drive. ;)

I believe it shows up as INSOLUBLES in the test.

Wouldn't the test also show acid levels?

The testing should tell you everything you need to know to make a decision on when to change it out. Everything else is pure speculation.

Danny

Take those cars out at least once a month on the highway. A good 50 mile round trip would be the best thing for them.

Your type of driving kills them quicker than anything, since the do not reach operating temp for a long enought time, nor do they get to blow out all the carbon and condensation that accumulates in the engine and exhaust system.

My work is only 10 miles from my house, so that is 20 miles round trip. All highway, but I know it is not enough, but I do this every other week. the other week, I take my daughter to be home schooled by my sister (My ex- an I have 50% custody and visitation, so week on week off). The other week results in 100 miles per day, so tha makes up for the 100 miles per week.

You do need to change your oil based on time, not mileage.

tarbe said "Besides, if it drives 240Joe nuts, it has to be worth doing! "

Craig said "Probably a short drive."

Ok, now I don't want to hear anyone say I started it, because they did.

Let's try a 3 pronged approach...the hard science explanation, the soft science explanation, and the emotional appeal.

The hard science: Soot is 0.03 microns in size, or 1.2 millionth of an inch....really really tiny. They have to use a scanning electron microscope to take pictures of it. Google it...you'll see. If the Soot doesn't clump, it can't do any damage...PERIOD, end of story. Soot is the only practical limiter in the length of time oil can stay in our old diesel mercedes, mostly because we have large sumps (8qts), and relatively light duty....130 hp AND an oil cooler. That oil is seeing easy duty. This has been proven time and again with oil analysis. Most of our diesels put about 1 to 2 % soot in the oil per 10000 miles. Modern synthetic diesel oil can easily handle 4 to 5 % soot, and Amsoil has one that handles 10%. Average fuel yeilds 4/1.5 is 27kmiles OCI. Good fuel and the EGR blocked yields 4/1 or 40kmiles. END OF STORY.

Now for the soft science: People that change their oil every 3kmile (even when the manufacturer recommends 5kmiles are engaging in a form of auto repair masturbation. They are doing an easy repair that doesn't really fix anything, but they like the feeling it yields. It is a mental illness just like excessive masturbation.

And the emotion appeal: Changing oil at 3kmiles versus the manufacturer's recommendation wastes approximately 1.1 trillion gallons of refined oil pure year in the US alone. It creates environmentally issues and funds radical mid-eastern governments. It costs our young sons their lives or limbs. It lowers our standing in the world. Most pro-3kmile changers are from the oil states...it's no coincidence that the infamous change it hot and ofter is from the great state of Texas.

I welcome any responses.

240Joe

You have a problem with masturbation too? There's just no pleasing some folks. If it wasn't for masturbation and changing my oil, I would have way too much free time on my hands. ;)