Oil change interval for lightly driven 240D
 

I have a 1974 240D (275K) that I only drive on the weekends. The odometer recently stopped working. How often should I change the oil if I do not hit 3000 miles/3 months? Is twice a year reasonable?

Twice a year may not be enough for shorter trips if that is the case, 3 possibly 4 at most though. I know this was not your question, but be certain to use diesel "C" rated oils of the correct weight for your climate.

Rather certain that car also has an oil reservoir in the injection pump instead of being pressure oiled, keep it full. Is there cap toward the top of the injection pump that reads "OEL" ?

Is it an oil bath air cleaner? Needs to be serviced also.

Very nice looking car!!! Good luck and please post more pictures...

It depends... how far do you drive on the weekends?

You can probably fix the odometer pretty simply. Not sure how similar to the 123 speedo, but I bet it is close...

2x per year is resonable.

In tradeschool I was told that some of the additives in the Oil get depleted after 6 months even if the vehicle sat in one spot for all of that time.
However, that has not been proven in any experience that I have had; and that was what Oil was like back in about 1975.

Sending your Oil to a lab is like twice the cost of a typical Oil Change. But, you might try extending the Oil Change for one year and then sending in an Oil Sample to the Lab.

If the the lab tells you the Oil Sample is still good to go you can increase your Oil changes time to once a year and in the long run save youself some money and the labor on the oil change.

Someone who knows about synthetic Oil might want to comment on if full synthetic Oil would allow the Oil change to be extended beyond a year.

With these cars and I think IDI diesels in general, it isn't the oil wearing out that requires the change, it's soot loading reaching max thresholds. So whether dino or synthetic, without significant extra filtration to remove the soot, OCI will remain the same.

Agree it is more about the soot loading so I'd stick with dino and just change it. Plus with 274K on the clock the rings are probably letting a little extra soot into the crankcase. The oil filter on that car is fun to wrestle with, a primary, secondary, can to clean and finicky bolt to get started.

Also agree the lab test costs more than oil change...go figure!!!

Two issues at play: 1) contamination, 2) delay of lube at start up.

In your case (infrequent driving) the issue becomes contamination -soot & water. Short trips usually result in high amounts of water contamination. If the run time is not long enough to get the oil temp above 100C/212F the water won't boil off. Water in the oil makes sludge. Sludge kills engines. (that's the short version)

If there are long intervals of down time between running, the oil eventually drains off the wear surfaces. This contributes to lots of wear on each start up. With recip engine aircraft that have sat for a long time, mechanics/owners turn the engine over w/ignition system (mags) turned off. Typically they will pull the prop through 20+ blades by hand to pump oil throughout the engine before starting. Big radial's get cranked by the starter for a few revolutions before the mag's & fuel are turned on. This tends to reduce the wear & tear.

Thank you for your replies! I drive it on the highway for about 20 minutes and then just cruise around the city running errands, so mostly short trips. I will change the oil 3 times a year to be on the safe side. Maybe I will start driving it to work one day a week so it sits less!

Imgur: 240D Photos

I do what the owners book says, not what the people trying to sell me oil changes recommend. Although, my mechanic did suggest I change it at 4000 mile intervals instead of 5000 due to the age of the vehicle.

Use synthetic and change it once a year. It's not the engine that will fail on the car- it's the body and the rest of the systems.

I'm afraid oil discussions have more "thoughts" and "feelings" than facts, so you may not get a definitive answer. They're the Oprah Show of car discussions.

I rarely put anything close to 3,000 miles on my car in a year, but if someone wants me to change my oil three or four or six times they're welcome to send the checks my way. :D

-Rog

Start-up lube on a diesel engine is generally not a problem since the fuel itself is a lubricant. This may be the major reason they are longer-lived than a gasser.

Also by keeping track of fill-ups you can keep track of mileage -within reason -till you fix the odo.

Neither my 84 or 85SD will spin fast enough to start in the winter on dino oil. They are good without plugging in with synthetic and relatively mild TN winters.

Perhaps send off to Blackstone and have an oil analysis to determine status of current oil. The Ram takes 3 gallons of Rotella full synthetic so having data to justify longer periods between oil changes is worth the price of analysis. I was told that I could increase from 10,000 to 13,000.

The SDs hold considerably less oil so the same economies don't hold. I may send of a sample at my upcoming change prior to winter anyway to have a starting point.

Hmmm... do you have glow plug issues? or compression problems? maybe the valves need adjustment?

above 0F the 617 diesel should spin fast enough with working glow plugs on dino oil.

maybe you have a weak starter, or bad ground or cable connections?