I changed the oil in my '85 300d in October 2015. From December 2015 to October 2016 it was driven only 500 miles or so. Maybe less.

The oil is Rotella Synthetic T6.

I know that in the old days, you were "supposed to" not leave dino oil in crankcase for more than 8-12 months, even if the car was sitting or driven very little. Or so I was taught.

Was there any truth in that old rule?

And if so, does it also apply to the synthetic oil sitting in my 300d now? I ask as I am getting ready to store it for the winter.

Do I leave it until spring 2017 or change it now?

By the way, the 300d is getting regular use now.

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

I don't think it would harm it with it sitting in there. My friend started and ran a car for a few hours with 12 year old dino in it, synthetic should probably be less prone to breaking down.

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Current: 1975 450SEL, 83 300D, 88 Yugo GVX, 90 300D OM603 swap, 91 F150 4.6 4v swap, 93 190E Sportline LE 3.0L M104 swap, 93 190E Sportline LE Megasquirt, 03 Sprinter, 06 E500 4Matic wagon.

I had wondered the same thing in the case of my 91 300D which gets driven only 2000 miles a year or so. Here's what my oil analysis tech said:

"The reason OEM's want to have at least an annual oil change it due to liquid contaminants. Condensation from hot engine and cooling quickly can result in water in the crankcase, and if the vehicle is only driven for short periods, it may prevent the lubricant from vaporizing any water out of the lubricant. The water in presence of high temperatures and oxygen will lead to oxidation deposits on piston skirts and rings.

"The second theory is the addition of fuel introduced into the crankcase which obviously leads to oil thinning and poor film strength and ultimately some friction contact.

"To be on the safe side, I would go ahead and bite the bullet and do an annual drain. In your examples it might make sense to switch to a good mineral based lubricant to lessen the economic pain when you have to drain annually on a lubricant that has few miles on it."

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 154k miles
06 E320 CDI "Rutherford", Black on Tan, 172k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 142k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

I have left oil even dino oil in for several years on vehicles that are not driven much, without haveing any troubles. However without doing an oil analysis you will not know if the oil is good or has been contaminated.

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1977 240D turbo

Always surprising how much you guys worry about things, I know of a 40 year old Leyland tractor that hasn't had an oil change in the 10 years I've known it and it's got a bad head gasket that puts jelly under the oil cap and an oil sheen in the top radiator tank

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1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...many, many years in the making....
1977 280> 300D - 500,000km+ (to be sold...)
1984 240TD>300TD 121,000 miles, *gone*
1977 250 parts car
1988 Toyota Corona 2.0D *gone*
1975 FJ45>HJ45
1981 200>240D (to be sold...)
1999 Hyundai Lantra 1.6 *gone*
1980s Lansing Bagnall FOER 5.2 Forklift (the Mk2 engine hoist)
2001 Holden Rodeo 4JB1T 2WD

Zach,
I believe only problem would be condensation in crankcase. On boat diesels, we would change oil in Fall & Spring if we were anal about it . In Fall because of acids etc built up during summer use and in Spring because of possible water contamination during winter storage. But those engine crankcases only held about 2 litres of dino oil.

My rule of thumb for cars, is change oil & filter once a year whether it's needed or not

However, on my 107, that doesn't do too many miles, sometimes I will skip a year after checking the "look" of the oil on the dipstick if I have hardly used the car. Or, I just change the oil and leave the filter till next year.

By the way, not everyone on the forum lives in a climate like ours - hot humid weather in summer and cold dry weather in winter.

All cars use Synthetic which I try and buy while in USA - crazy prices here in Canada.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

I prefer an oil change before storing in the fall, removes the contaminates and oxidized oil that can cause corrosion, restores the oil's protection.

In the spring some have mentioned changing due to moisture, that's why you take it out for a nice long drive to evaporate any moisture, ... I like to stick with 1/year on my low mileage car.

Daily driver isn't a problem at 3,000miles/month.

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Gone to the dark side

- Jeff

I saw this video several years ago, good reason to change your oil once in a while.

https://www.youtube.com/watch?v=AhVo7-gzJo4
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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

Daughter's car was stored while she was at college for 4 yrs. Driver maybe 50 miles a year. Tested the synthetic oil a few weeks ago on my oil tester. It showed 5 out of 10. Still good to go.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Interesting! Is this Nearly two years later, we get our hands on Lubricheck's "blood tester" - Autoblog https://www.amazon.com/Lubricheck-Motor-Oil-Tester-Instantly/dp/B00HBAG9AC what you have?

Does it work equally well with diesel engines?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

This review Oilyzer tester: the Do It Yourself oil analysis, but don't forget lab quality control - Read expert review at epinions.com says not approved for diesel.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

I saw that video many years ago, and that's why the very first thing I did to my SDL was change the oil. It had sat undriven (not even started) for 10 years in an empty lot. The oil still ran out of the drain plug fine, but there was some residual sludgy crap that had to be removed from the pan and the oil filter housing. Was like a thin-set jello......NASTY!

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Changing the oil is just so cheap I don't understand why we ever see threads like this. On my low milage BMW, using synthetic since new, I stick with the factory recommendation of oil changes at least annually. Like others have mentioned, I've been told it has to do with moisture in the oil, but I don't really know for sure. I guess I'd rather throw a little bit of money away on overzealous oil changes than rebuilding a motor.

Most new gasoline cars have a sensor to detect when the oil has become too sooty and needs changing, often allows up to 7000 mile interval. Thus, use is more important than time. Those in the southwest U.S. have less worry, or if you keep it garaged in Quebec, since condensation is the main threat to sitting. The downside in changing too often is waste, cost, and time. I don't know if new diesels have a similar "dirty oil" sensor. The oil gets dark very soon in my 1980's diesels.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

My bluetec has a 1year/10,000mile interval, whichever comes first. As my first 10,000miles occurred in 10weeks, and it is mostly highway, I don't know if it would be triggered sooner on the "severe service" schedule if I drove short distances or towed, might simply be miles/time in the car's computer.

If I were creating an algorithm for oil changes it would be based on gallons of fuel used and time. If you're using an engine harder or for short distances the fuel/mile is higher as is the oil contamination. Oil consumption in my Caterpillar engines was measured as a function of quarts of oil per gallons of diesel, which makes a lot of sense in applications where you might be using a lot of its capacity, or running easy. Cars can be used for soccer mom short drives and lots of idling, or road-warrior miles, or towing, ... lots of condensation starting cold in cold climates and not warming up thoroughly or run long distances where no moisture will survive the heat, ...

I have to agree with Bob: if you have a question, go the safer route.

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Gone to the dark side

- Jeff