Though I know this question probally came up before; what is the best manufacturer and grade of oil for use in an 85' 300D. I have been using Mobil 1 15w50 but I don't think its appropriate for winter; in which I use 10w30. My concern is that these oils are very different in viscosity and recommended opperating temps, but Mobil doesn't make an "inbetween" grade; Oh I wish mobil made 10w40 in full synth. Does anyone have any advice on this subject as for grade and manufacturer (I love Mobil products and use Mobil 1 in all my cars) as I live in SE Pennsylvania and it is getting time for an oil change. I have heard about Mobil Delvac 1 but could only find a dealer over an hour out, that wanted over $100+ for 4 gallons( min quantity sold).

Any advice appreciated.
TIA
Dr. Adam T. L. Delecki

I and other 300D owners I know in California have used Mobile One 5W-30 for many happy hundreds of thousands of miles. I live in the Napa Valley. Triple digits are common here in the summer. I find that my oil is perfectly (I have had it tested by Amsoil) healthy at 3000 mile change intervals. I prefer a lower viscosity oil for start-up protection. We have cold, dry, winters - single digits. Amsoil makes a quality 5w-40 sythetic, it is avialable on theire website www.amsoil.com. But since they claim
my Mobile one is ok at 3000, I have not seen a reason to switch.

Luke

304,128 happy 5w-30 Moible One miles.

__________________
'78 300D 310K Maple Yellow / Bamboo
'87 300D 81K Barolo Red / Safron (RIP @ 113K)
2003 E320 34K Pewter/Charcoal
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I use 15w40 every 3k.

Oil has been batted about in these forums ad-nauseam. All long lived cars have one thing in common: the owners feel the best oil is frequently changed oil.

__________________
'78 300D 310K Maple Yellow / Bamboo
'87 300D 81K Barolo Red / Safron (RIP @ 113K)
2003 E320 34K Pewter/Charcoal
-------------------------------------

According to the ExxonMobil website, there is a Mobil 1 0w40. I have not seen it sold anywhere and the website doesn't even have it in their little spec chart or their online store, so perhaps it is a brand new product. The pic shows that it has a black cap...

I'd love to get my hands on a couple of cases and give it a try--sounds like the perfect all-around diesel oil!

-Joe

Luke / Others,

I am just starting to look for my first diesel... so I am collecting words of wisdom from the more experienced folks here. I know diesels need a frequent oil change to rid the soot / contaminants. You mentioned you had your Mobil 1 tested at 3K. Did they recommend you could go longer? I have seen a few mentions in the past about just a filter change mid-term and then a longer oil change cycle. Has anyone implemented that approach and had good long term results?

Thanks again and still searching for that first one.

Chuck

I've been running Agway 10W30 in the winter, and Chevron Delo 400 15W40 at temperatures above 50 deg F. Both are non-synth though.

__________________
Bob Roe
Lehigh Valley PA USA
1973 Olds 88, 1972 MB 280SE, 1978 Datsun 280Z, 1971 Ford T-Bird, 1972 Olds 88, 1983 Nissan Sentra, 1985 Sentra, 1973 230.6, 1990 Acura Integra, 1991 Volvo 940GLE wagon, 1983 300SD, 1984 300SD, 1995 Subaru Legacy L wagon, 2002 Mountaineer, 1991 300TE wagon, 2008 Murano, 2007 R320CDI 4Matic 52K, some Hyundai, 2008 BMW 535xi wagon, all gone... currently
2007 Honda Odyssey Touring, 2014 E350 4matic

another one of these oil threads but come on guys and gals - why in tarnation would anyone want to run Mobile 1 in a vehicle that they are changing the oil in every 3000 miles? I have a friend who is a lubrication engineer for Mobile and I have asked him I don't know how many questions and yes Mobile 1 is one of the best oils out there but I'll be goldurn if I am going to put it in a car with 200,000+ miles. In my opinion, if you are changing it every 3000 miles then Delo400 is as good as it gets.

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Jim

MB specifically does NOT recommend any 10W40 oil from any manufacturer. Period. Mobil 1 15W50 is fine, as is any other 10W30 oil from any major vendor. Probably don't feel that the wide range oil viscoity extenders give adequate lubrication at one end or the other.

I wouldn't use 0W or 5W oil in a diesel -- probably not "stiff" enough, synthetic or not, to stand up to compression stroke pressure on the crankpins. Fine for gas engines, but not diesels

15W50 isn't going to be significantly different from 10W30 except maybe below -10F.

See some other threads for leaking/burning problems when changing from dino oils to full synthetic. I've not presonally seen it, but have heard of it. Personal experience is that if it leaks or uses oil now, it will get worse, if it doesn't, no change.

Oil testing is cheap ($7.50 at the local Caterpillar shop for a test kit you send off) -- good investment, especially if you want to use longer change cycles. Volvo recommends 7500 miles for their TD, with filter change at 15000. I use Mobil 1 (same oil consumption before and after, about 1000 miles to a quart), and change the filter every time. No real trouble, although I need valve guide seals and it is getting harder to start at 212000.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

They sell it at my local Pep Boys, I woulda got it but I was still looking for Delvac 1. I ended up just getting Mobil1 10w-30 full synthetic.

__________________
2005 Audi A4 1.8T CVT -Silver/Black "Siegfried"

1982 300D - Silver/Blue "Ralph" -For Sale:
http://www.peachparts.com/shopforum/showthread.php?p=852260

1989 VW Diesel Jetta Blue/Blue "Bodo" RIP

After 23 years and nearly a half a million miles in MB diesels (all using synthetic oils) I can make a few observations... I have lots to share but it would take a few volumes...
I've run my 78 300CD since about the 10,000 mile point on the lighter Mobil One oils.. starting with their offering in the late 70s of 5W20. The main advantage as a user was that the car seemed to have nearly 100% of it's power available as I pull out of the driveway. A few times I ended up with 15W50 dino oil when shop neglected my instructions to use the syn and the car was SLUGGISH for the first 3 or 4 miles as the engine seemed to fight the cool thick oil. Over the years I've stayed mostly with the 10W30, even to this day, on a 288,000 engine that is all original, running fine, and very little oil consumption between the approx. 3,000 mile change intervals. Occasionally I would put in the Mobil One 15W50 synthetic. After startup I could feel the difference.. a little sluggish, but not nearly as much as the dino stuff.
Only recently have I switched to the Delvac One. (5W40 I believe) This is mainly due to the expense and limited availability. (have to travel to get it) The main motivation to switch is a desire to keep my much newer 1990 350SDL running as good and wear free as possible. The Delvac has better soot tolerance and slightly wider viscosity band then the other syns. (although I must point out that the viscosity numbers for a syn oil are much less of a concern than they are for dino stuff) For the last 25,000 miles in that car I have used 4 different viscosities and two brands of oil, changed each at 4,500 miles and had oil analysis done by the same lab each time. I used 2 different weights of the Mobil 1, Amsoil's best diesel offering, and the Delvac 1. While the wear rates were very low on all samples, the significant wear metals in the Delvac 1 were half that of the Amsoil and about 20% or so less than the other Mobil 1 weights. In all cases the condition of the additive package was so good that the oil had used less than 10% of it's life EXCEPT in the area of soot content. This is THE determining factor in change intervals for diesels. Only those that add a very good bypass filtration system (less than 2 micron perhaps) can you seriously consider extending change intervals. Conventional filters will not do the job no matter how much you change them. Once one makes the decision to use an oil like DelvacOne it becomes good economics to do the bypass filter install so changes can then be extended to many tens of thousands of miles safely. (WITH oil analysis!) That is my next move I think.
A few things to remember...
Newer diesels (1995 and newer mostly) produce less soot per mile than the older ones. A worn engine produces a lot more.
Frequent enough changes of conventional oil WILL give many hundreds of thousands of trouble free miles in these engines. However, the use of the synthetic will provide better lubrication at startup, greater life and less wear in the hottest areas of the engine, (turbo bearings & valve guides) slightly better fuel economy, and much easier starting in cold weather... especially with the older diesel engines using the loop-style glow plugs. (I recommend converting to pin-type anyway)
I would not counsel anyone to extend the drain interval of the syn oils any longer than you would a good quality (CH-4) rated conventional oil without careful monitoring. (analysis) The only case I would strongly recommend the use of a good synthetic is for turbocharged engines. Mobil One oils have a high temperature tolerance that is roughly 100 degrees higher than good dino oil. This capability is of great service when someone (other than YOURSELF naturally!) thoughtlessly pulls off the freeway after a 5 mile, 7% grade climb at 70 mph on a warm day then shuts the engine down. Oil cooling of the turbocharger's bearing assembly abruptly stops and the very high residual heat in the exhaust turbine migrates right down to the shaft raising it's temperature dramatically. This will coke all but the best of oils. Enough of this treatment and your turbo is leaking and the car starts ingesting oil through the turbo and/or out the exhaust. A good syn oil gives you a nice advantage here.
More thoughts:
A good synthetic 5W30 provides better lubrication than a dino 15W50. Conventional oils get a lot thinner at high temps and a lot thicker at low temps than synthetic oils do. (note that the pour point of a 15W50 syn is only a FEW degrees higher than the 5W30 syn, but both are FAR lower than even the lightest conventionals!)
I would stay away from Castrol Syntec. My memory is foggy on it, but there were some lawsuits a few years ago where Syntec was judged not to be a true synthetic, and a little fast and loose with it's claims.. Syntec's base stocks are of a different chemical origin than MobilOne/Amsoil... one uses POH base stocks, the other uses esters.. (forget which one is which)
Also, I wouldn't go to a 0W30... never tried it, no reason to.. Unless perhaps I lived at Point Barrow, Alaska.. even then the 10W30 would be fine.
Wives tales: "Changing to synthetic will cause the engine to leak!" Fugedaboudit... was true many years ago to some degree due to chemical incompatibility with some seals when combined with certain synthetics... not so anymore. If you have a leaker it may leak a little more, but a tight engine will not begin to leak on syn.

In the way of background... I live near Denver, Colorado and can successfully start my 1978 300CD WITHOUT a block heater down to 15 below zero here at 5,750 feet elevation. I think that speaks well for synthetics... after all these years and miles the engine is still tight enough to light off in these conditions... Remember, starter rpm is VERY important for cold weather... especially at high altitudes. Conventional oils slow starter rpm considerably at very low temps.

I hope this wasn't over-long, but felt obliged to share what I've learned over the last too-many years on the subject... These are mostly fine points on the use of synthetic oil.. I want to reiterate that good maintenance and frequent changes with good quality conventional oil will yield excellent results... in fact my philosophy would likely NOT survive a cost benefit analysis. My habit of using the expensive syn oils and still changing them ever 3 to 4,000 miles would likely pay for a lot of repairs, maybe even a new engine on the 300CD over the 430-some thousand total miles between the two cars! But, for me it's peace of mind.. The inside of both engines is squeaky clean.. no hint of any tarnish or sludge... and no worries about starting or wear. From a $$ standpoint it's probably questionable, at least until I do the bypass filter system, but I love these cars and want them to know it.
Good luck!
Dennis
Arvada, CO

Dennis,

You've convinced me to atleast try synthetic oil as soon as my Rotella needs changing. However, do you recommend that I get the Amsoil or Mobil1 10W30 stuff? There has been so much discussion on the compatibility of Mobil1 with diesel soot that I'm still just as unsure now as I was when I started reading all these oil threads. What has your analysis shown you about the difference between the two? The price difference is negligible (The amsoil is $48 or so for a case of 12 qts, the Mobil1 is $21 for a case of 6 qts).

Also, what is involved in this Bypass filter system? I've run out of things to do on my car and it sounds like an interesting useful project.

Thanks for all the information!

Alex

__________________
1983 300D (parked for four years)
2012 VW Sportwagen TDI Manual
2001 Miata SE
1962 Chevrolet Corvair Rampside

Yes, this bypass filtration system sounds interesting; but what exactly do you mean? Does it use a different type of filter, or does it require the entire engine oil filtration system to be changed?

I have used mobil 1 and am happy with the results, but my concerns are that at every 3000mi, when I change my oil, it's always jet black, and have been looking for something that will stay cleaner longer. I don't think that the sulfer enriched dirty mobil oil does much good cleaning when it gets to that state; that is why I am considering delvac 1 (as it's meant for diesels).

Please let us inquiring and tinkering forum folks know about your filtration system. I'm sure we'd all appreciate hearing about it.

Sincerely,
Dr. Adam T. L. Delecki

Hello Adam and Alex..
Firstly, regarding the bypass oil system..
The most popular "bypass" oil filter system is offered by Amsoil. For our diesels it involves no change to the present oil system. You merely tap a pressure point in the engine oil system (usually the pressure sender port) and run a line to the filter canister that Amsoil sells you. This is a very dense filter that will trap very small particles and as such cannot support the full flow of the oil system. With some time it will clean the oil of the larger soot products that cause wear thus allowing extended drain intervals. The return line from the filter is usually connected to the oil pan or top of the valve cover. The system sells for AROUND $160 (not sure of this) and is designed as a do-it-yourself project. Alternatively you can take it to your favorite mechanic.
Many long haul truckers use this type of system and can extend oil changes on Delvac or Amsoil to 100,000 miles or so. Periodic analysis should be performed and the bypass filter unit changed at regular intervals. When changing the filter you lose a quart or so and replacing it is usually enough to renew the additive package for continued safe use.
Adam you mentioned you want an oil that "will stay cleaner longer"... Well, believe me, this is NOT what you want. The oil contains chemicals which are able to hold the soot in dissolved suspension up to a certain concentration. (between roughly 2 to 4% or so) When sufficient soot has entered the oil that the additives can no longer handle the soot condenses in to nasty little particles that will begin to scour the cylinder walls, bearing surfaces, etc. Even at very low soot concentrations your oil will be black to the eye and look dirty. It is doing what it's supposed to do by keeping the soot dissolved in IT instead of attached to engine parts. It is hard to tell the real condition by looking at it. Installation of a good bypass filtration system may be able to keep the soot levels down enough to have the oil look clean to the eye, but I'm not sure since I don't have one. It will, however, keep the oil from circulating the big soot nasties.
Alex.. without going to dig out my oil analysis reports, I can recall that the additive package was a little different. The Amsoil contained different levels of some additives to help sustain extended drains which Amsoil promotes heavily. (additives do much more than suspend soot) From a soot suspension standpoint both the Amsoil Diesel oil and Delvac One have the highest soot rating so there shouldn't be much difference between them. Remember: All Mobil One oils carry at least a CF rating making them suitable for diesel engines. But the Delvac One will handle more soot than the others. So, I'd highly recommend staying with manufacture's recommended change intervals with the 5 to 10W30 stuff. As far as soot goes I changed my oil in the 350SDL after 4,500 miles of good hard driving. The soot percentage ran between 2% and 3%. Delvac One can handle up to 4 1/2%. I don't remember what the others can handle, memory says it's around 3%. I did get SLIGHLY lower wear rates with the Delvac One, but the numbers were all so low I think they're statistically insignificant.
I hope this helps guys!... we're really discussing very subtle differences between several VERY good oils. Mobil One 15W50 is slightly more sluggish on a cold startup than the others... but it's a very good oil for high temp hard running, (and turbos) The lighter ones give very easy starts, tiny bit better mileage, but probably not quite as much ultimate protection in hard hot running, but still more than the best conventionals.
Take care!
Dennis

Was out of net for a few days.

I normally comment on any negative comments re: superior products.

Generally, the comments on synthetic oils are getting more intelligent (I know, I know, just my opinion) ... there was one that said it was "too expensive" every 3K miles, though. While an honest opinion, just like mine and others, it is simply too black and white negative relative to the amount of information that is available on use of synthetic oils and lubricants.

Simply put - synthetic lubricants are better. They are better at everything relative to the non-synthetic alternatives.

__________________
George Stephenson
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg