Hello all,

on sunday i changed the oil in my 87 300sdl (225k). i purchased car in june 08. had oil changed at my indy as no one in town stocked the filters and i was headed out for a lil road trip in august. Ok so now i get a filter, get some Rotella 5w-40 synthetic and change filter and oil. car ran noticably rough on startup and also did yesterday and today on statup (but getting better maybe this is normal when very cold out)but runs better once warm and also quieter. but when i initially started it up after the new oil change it blew black smoke and black stuff out the tail pipe (had an old gas engine truck that blew black stuff that meant it was running rich). from what i was told the the p.o indy that i bought car from (not my indy but his friend) it had regualr oil changes and didnt require synthetic. did i create a problem by switching to synthetic or is this simply the synthetic cleaning crap out of the engine and some ends up in the tail pipe on startup?

sorry if this has been covered but i have searched around on this forum and others and cant find much info. if it has been covered, just supply me with a link.

thanks
Ron

where did you fill it up to?

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You know you are not supposed to put the oil into the fuel tank, right?

Just kidding, just kidding.

Welcome to the forum. One quick note before we continue is that you should really add your location to your profile so that it shows up in your posts. Even though you stated what car it is for you should add your car to your signature as well for future questions.

Now...

You didn't notice this at all before? No smoke at all on start-up? This doesn't seem like a symptom of switching to synthetic motor oil. BTW- Rotella is not REAL synthetic oil. It has some same properties so it is labelled as such.

Did you do anything else besides an oil change? How did you do the oil change?

I would say check the oil level, make sure that is fine. Then just keep an eye on it for the next few days to see if you notice any differences.

Others will chime in...

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2009 ML320 Bluetec
1985 300CD
1981 300TD

Past Mercedes
1979 300TD
1982 300TD
2000 E320 4Matic Wagon
1998 E430
1984 300SD
1980 300SD

ok oil level right now when warm and running is right between the high and low marks on the the dipstick. no nothing else was done, other then getting oil all over my driveway. the black spitting was only on inital startup but it seems to smoke more then usualy on startup, maybe im just not aware this happens when its cold as this is my first winter with a diesel.

i live in chicago

you should do some searching on that. I was under the impression engine was off and warm nad the level should midway b/w marks

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hmmm ok i'll go warm her up, drive to gas statin shut it off and check oil. if i dumped in 2 gallons of oil thats 8 quarts right?

right, but if you do the metric to imperial conversion accurately, its a little less, and there are other factors. Best to start low and add.

Make a note of what it took and reference for the future.

and search first.. I could be wrong.

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8quarts should be about right.

Check the oil cold, won't be a significant difference.

Synthetic oil, or any type of approved engine oil of the correct viscosity will not change the way the engine runs or smokes.

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Gone to the dark side

- Jeff

That is not entirely true. A cold engine that doesnt smoke on 15w40 might smoke a bit until warm on 5w40. Thinner oil can mean more oil in the cylinder. Also with synthetic more oil will stay on the walls.

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http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

You may want o reference the thermal coefficient of expansion for engine oils. I thought over normal temp differences they can expand 10%

Edit: Did not realize the engine model.

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The only thought I have is the change to lighter weight 5W40 oil instead of the standard 15W40.... At 225K the rings are probably a little worn and you may be getting some of the lighter weight oil moving past the rings on cold startup causing the smoke. Its the 5W portion of the blend that is suppose to be the top end lubrication in low temperature starts and that is burning off.

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FRED

Daily Driver: 98 E300TD 199K
Hobby Car: 69 Austin Mini
Past Diesels: 84 300SD, 312K
87 300SDL, 251K
94 Chev. K-1500 6.5Ltr.TD, 373K

My first thought was why are you using 5W40 oil?

Check your owners manual and use the recommended oil year round.

Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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My thoughts also.........if it is to facilitate better cold weather starts in Chicago I would switch back to 15W40 and use a block heater. Or try half 15W40 and half 5W40 Diesel rated oil for the winter and see if the old tank stops smoking.

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FRED

Daily Driver: 98 E300TD 199K
Hobby Car: 69 Austin Mini
Past Diesels: 84 300SD, 312K
87 300SDL, 251K
94 Chev. K-1500 6.5Ltr.TD, 373K

And exactly what viscosity would this yield?

__________________

Gone to the dark side

- Jeff

A TRUE synthetic multi-viscosity oil is different than a multi-viscosity dino oil.

It's all about what the SAE viscosity rating is, and how it came to be.

In a standard motor oil, lets say a 30weight, it gets thicker when cold, and thinner when hot. That is the nature of oil, and used as the standard for oil viscosity ratings. So, if it stays the same thickness at all temperatures, it is not considered a 30weight oil.

Still in the standard/dino oil, many engines will perform better without the very thick oil cold, but can't have the very thin oil when hot. What the oil manufacturers do is take a thinner oil, for a 10W-30 it will be about a 10weight oil, and add short-chain polymers (viscosity modifiers) to make it thicker when hot. Problem is: these additives are poor at protecthing in high-shear areas and don't protect like a 30weight, more like a 10weight or 15weight, so the engine manufacturers can't have that, specify a higher like 15Wxx or 20Wxx.

Enter the full-synthetic oils. Mobil 1 5W-30 will be the example here, since it was manufactured with almost NO VISCOSITY MODIFIERS to break down. The reason it is a multi-viscosity oil is that the synthetic oil naturally stays thicker when hot, and doesn't thicken as much when cold (remember the old Mobil 1 commercials?). Therefore, a 5W-30 synthetic will protect better in high-shear applications in an engine at all temperatures than a dino 10W-30 or even a dino 20W-40, but perhaps not as well as a dino SAE30. This allows those of us who understand lubrication and oil ratings to go slightly outside of the oil rating charts for dino oil when selecting a synthetic oil for our cars, ... such as a 15W-50 for year-round etc.

In short, a true synthetic 5W-anything is not going to have less oil pressure cold-starting in the winter than a 10W-anything dino oil, because it is still thicker than it will be at running temperatures, thicker than the manufacturer has determined is necessary, and it's going to pump-up faster to lubricate the engine since the pumpability of a not-too-thick-from-cold oil is much better.

Sorry to ramble on, trying to put a complex and outdated rating system into reasonably simple terms for comparison, it's probably the most misunderstood part of cars' regular maintenance and the reason people don't understand synthetics.

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Gone to the dark side

- Jeff