Mercedes specified 229.1 or 229.3 for these engines IIRC.

With each succeeding generation newer and better oils come out for them.

Looking at MB oil specs with the Lubrizol oil comparison tool https://online.lubrizol.com/relperftool/pc.html , the later generation 229.5 - 229.71 oils outperforms the original spec significantly in every way.

Are these higher spec oils ok for use in these older engines?

I dont expect them to last as long in these old mechanical injection lumps of course, but it's nice to have the increased performance during the fill.

Along with the general advantages of dino vs synthetic, I recall seeing snipets of much longer timing chain life with synthetics.

There's nothing special about the lubrication needs of this era of MB diesels, aside from being diesel rated oil. Any oils that carry industry-standard certifications are more than adequate. And there's no need to shorten the change interval "because of age" - 3,000 mi. on conventional or 5,000 mi. on synthetic is a minimum of what modern oils are capable of in these engines. My go-to is a 5w40 synthetic, or a conventional 15w40 if it uses or leaks a lot. I have 10w30 syn-blend in two of mine right now and it's performing very well - no increase in the amount they use, either.

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'82 300CD
"Pearl", the very first turbo diesel 123 coupe
Totaled 11/23/18, rebuild in progress.
'85 300TD, "Artemis".
'78 300D euro, "Ol' Red", mostly retired.
'85 300D, "Gandalf".

I understand, these motors are tanks and run for a long time with a modicum of maintenance.

I would like to take advantage of the oil technology that outperforms the original oil spec, as oils improve prices go down to not much more than an older spec oil. Just not sure if there were any special considerations that might make them not optimal for the older engines.

For example, newer spec oils are low ash because of DPF's. I wonder if formulating for that will cause a problem for older engines like the 603.

I hadnt seen any problems browsing the net so far though. I came across a lot more posts about studies with double the timing chain life with synthetics and will be switching my new to me 300D to that if there is nothing wrong with it.

Lots of million milers with regular dino oil changes...maybe we can get 1.5m with top tier synthetics?

Sigh...

This **** again?

Use what your book says. Brand is irrelevant. They are all better than what you need.

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Rindfleischetikettierungsüberwachungsaufgabenübertragungsgesetz

At the cost of propagating further discussion on the same old topic, I'd like to point out that...Newer specs focus on emissions equipment longevity more than anything else. A whole lot of the really good anti-wear additives are being removed. Zinc+phosphorus are in smaller and smaller quantities in the newer oils (ie. ZDDP or "break-in" additives) which are highly important to engines like the OM60X and OM61X engines that have flat tappet cam/lifters.

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{2010 Mazda 3 266,000mi} - daily since new, Airlift suspension + some chunky sway-bars: fastest pass 17.7@77MPH
{1987 300SDL 256,000mi} - stock turbo @ 22lbs straight piped + a whole bunch of pre-turbo water/meth injection, 722.3 with increased line pressure, special sauce, and shift kit: fastest pass 16.5@82
{1992 964 Carrera 4 Frankenstein ??,???mi} - 993 forward dated, Speedster conversion, GT45 + E85: fastest pass 12.5@113

When the book is 30 years old, wouldnt you wonder if there is better out there?

There is. Literally the cheapest oil you buy today is light-years ahead of the best you could buy when the car was new. Use the weight the engine was designed for and move on with life. Buy something off the shelf - ANY shelf - and quit losing sleep over which oil is the "best".

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

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

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

True! But comparing the older specs, it looks like there are improvements in a lot of relevant areas like resistance to wear, sludge formation, deposit formation, and oxidative thickening?



But then again, peculiarities of our engines like the flat tappets you mention, may outweigh the benefits of the newer oils in our motors?

But...IIRC the lessened anti wear additives are due to the DPF system, but these oils still spec less wear, so they may have different additives more friendly to DPFs to replace the usual Zinc/Phosphorus, that can then adequately lube flat tappets?

Then there is the info floating around of the significant timing chain life increase with synthetic lubes.

Been away from old Mercedec diesels for too long, just catching up.

Will try to look for UOA's of OM603's also.

The 603's aren't anywhere near as hard on their oil as the 617's. Rotella T6 is about as good as you can get for mainstream synthetics for a 603. They're quite happy on it. The higher spec oils with the reduced additives are for DPF systems and typically have high-pressure additives removed. I'm sure you could add a treatment to get those properties back, but why when a suitable oil is already available?

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

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

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

I have the time. PO just changed the oil with God knows what before I bought it, and am sick in bed with pneumonia. So this is actually theraputic for me.

But yeah, it can be as simple as that. I think I will be looking for those threads mentioning studies of twice the timing chain life, and see what oil that was. And look for OM603 UOAs if there are any.

Absent that, I understand the oils nowadays are pretty good and these engines not so demanding on them anyways as long as the intervals are reasonable. Not like on something like a turbocharged Subaru that can kill low tier oil fast.

Funny, T6 is also highly recommended in Subaru circles. Good oil!

Yes, I'd like a pour and forget oil, just trying to find an oil that will suit our engine's design the best.

So in an ideal world Id be looking for a synthetic with as much high pressure additive as possible. Maybe thats why some of the old oil recommendations were so thick, 20w40 and 20w50, (can you even get them anymore lol), for a thick boundary layer in the cam area?

Mobil one recommends using their FS 0w-40 european car oil in both the OM603 and the OM617, it meets 229.5, 229.3, and CF ratings. I would think this would be a good oil to use especially since technically MB says we should be using 229.5 oil in all of the older engines.

I used this a few times on my 603, but noticed it looked and smelled like gas engine oil, it was light colored not dark like the HD diesel truck oils I am used to using. So it must have a very different additive or detergent package than the HD oils. I did read someplace that MB recommended oils that hold 2% soot, instead of the diesel spec 4% though, so maybe it's ok.

I have been thinking about going back to the 229.5 oils instead of the HD truck oils I have been using lately in my cars but i'm not sure.

Interesting MB and Mobil recommend that, I hadnt known.

A Cx rating is a step in the right direction. Although I wonder why Mobil pushes the Euro 0w40 over Delvac 1 for this application, I see many recommendations for it from OM603 owners online, some proclaiming it the best oil even.

On the oil forums there is quite the differemce between HD and PC oils in general, but they do say smell and color is not much of an indicator of anything nowadays.

On the soot, from what I read I believe MB wants a max of 2% soot load on the oil and to change it out at that point, but newer oils can safely hold significantly more?

Also, about ZDDP...interestingly, most of the Cx spec have a lot of ZDDP in them. But...apparently there is 2 types of ZDDP, one commonly known for anti-wear, and the other for adhesion of oil to metal parts. Cx spec need lots of ZDDP because the detergents are counter productive to lubrication qualities. So yeah, lots of ZDDP but more of type 2 to make up for the detergents.

So right now I am not closer to having a clear preference lol...but I do know pretty much any modern rated oil will not cause any problems and will do fine.

Honestly, had an easier time zeroing in on an oil for the Legacy GT and CLS55 lol!

Paralysis by Analysis. Pick an oil. Use it.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

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

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

True lol, but oil change on this car is a ways off anyway so just satisfying curiosity till then.

Probably will end up going with a 5w40 synthetic HDEO or whatever 229.3 or .5 oil is on sale when change time comes.