Used to own an 84 300sd as well, still miss that car! It was great for road trips. I ran Rotella T6 in it and changed around 7500 miles. Bought it with 150k miles and put about 120k miles on it before it was totaled. Mobil Delvac 1 5w-40 would be solid choice as well, but seems harder to find than Rotella. At least in my neck of the woods.
Question about Rotella T6 oil for my 84 300SD Mercedes
- Thread starter revdarkwing
- Start date
Your vintage Mercedes probably specifies an oil that meets “SF/CC/CD” in the owners manual.
A specification that is 40 years old, and absolutely obsolete at this point.
Modern oils are so much better.
That engine shares the same basic architecture, although with an extra cylinder and a turbo charger, as the engine I had in my 1981 MB 240 D.
Any diesel oil meeting a modern specification will be fine in this car. My preference is for the synthetics, because cold start with those glow plugs can be a bit of a challenge,
The oil will darken almost instantly after an oil change, and that’s not a big deal.
The secret to longevity with this engine is:
1. adjust the valves when they need to be adjusted, and you will need a special wrench set for that. If you’re near me, I can let you borrow the set.
2. Clean fuel. Change the filters every year.
3. Change the oil to reasonable interval, and 5000 miles is reasonable.
4. Don’t make any stupid modifications to increase the power. People would bypass the turbo control system on this to raise the boost level. Don’t do it.
This is one of Mercedes great sedans. It’s a bit slow, but the rest of the car is built to an incredible standard of quality. You can drive this for as long as you like.
I had two 240D’s, a ‘79 and an ‘83- I still have that one. Ran Rotella exclusively in them, soon for the first 10 years, then synthetics, and did 5-6K ODIs, Mann or Purolator filters. The ‘79 got totaled at around 280K, ran good. The ‘83 still has 300psi compression, but with the usual valve cover and lower oil pan drool. I’m running Delvac in my ‘97 Jetta TDI, Mann filters, 6K ODI, only because a friend gave me a bunch of it, when he stopped driving semis. Seems to be working well.
I have an ‘04 Jeep Grand Cherokee from Europe with the MB 2.7L 5 cyl CRD. Bought it at just under 100k miles. I started out using the “approved” M1 European 0w-40 but soon switched to T6 5W-40. I’m up to 200k and the T6 seems to be working well at ~9,000 (15,000km) oil change interval.
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What about some Pre DEF oils....Amsoil makes a synthetic 15w40 and Lucas has a conventional 15w40.
https://www.amsoil.com/p/amsoil-15w-40-heavy-duty-diesel-and-marine-oil-ame/
https://www.lucasoil.com/product/15w-40-magnum-high-tbn-ci-4-oil/
https://www.amsoil.com/p/amsoil-15w-40-heavy-duty-diesel-and-marine-oil-ame/
https://www.lucasoil.com/product/15w-40-magnum-high-tbn-ci-4-oil/
The European ACEA association started in 1991, well after your car was made. Before that it was CCMC which started in 1972. Any European or OEM oil standards for the 80's are now well out of date and probably unobtainable.
Good luck getting a newly made CCMC oil anywhere.
Yes a modern API CK-4 oil is much better than anything used back in the 80's. A 40 grade oil from Delvac, Delo, Rotella etc would be my choice.
Good luck getting a newly made CCMC oil anywhere.
Yes a modern API CK-4 oil is much better than anything used back in the 80's. A 40 grade oil from Delvac, Delo, Rotella etc would be my choice.
As an owner of several older MB diesels in the range of yours I will say that any Diesel oil will be fine. I ran a 1995 E300D to right at 500K on Rotella T6 (might have been T4 in the beginning) with ZERO engine issues. I had an 83 300TD-T, 84 240D (gray market car), 85 300TD, another 83 300TD-T and another 95 E300D, nothing but T6 in them all & never an oil related issue.
Several have suggested valve adjustments and I second that pretty hard. I chuckled real hard about the vacuum leaks that appear at the absolute worst times. It's always fun to pull up at a nice restaurant and have to raise the hood to shut it off; been there, done it, LOL.
GREAT car that you can keep forever as parts are available. You should have a wonderful experience owning one. The ride is so unique, these cars were way ahead of their time.
Enjoy!!
Several have suggested valve adjustments and I second that pretty hard. I chuckled real hard about the vacuum leaks that appear at the absolute worst times. It's always fun to pull up at a nice restaurant and have to raise the hood to shut it off; been there, done it, LOL.
GREAT car that you can keep forever as parts are available. You should have a wonderful experience owning one. The ride is so unique, these cars were way ahead of their time.
Enjoy!!
Check the viscosity recommendation in the owner’s manual. If you don’t have the manual, I am going to guess any good 15w40 with a Mann or MB filter every 5k and the engine will outlive you. Synthetic is fine but not necessary. The 126 is a car from the time when Mercedes was built to a standard, and not a monthly lease price point. Some of the best cars ever made. That quality ethos changed around 25-30 years ago. Now they are fine but not special like the 126 was relative to peers/. Good luck and happy motoring!
JHZR2
Staff member
Don’t know how I missed this thread.
Daimler recommended the following for the OM61x series engines:
This chart I think was newer. CCMC G5 was a precursor to some of the ACEA ratings but implied more robust oils.
Folks recommend 5w-40 because older, high mileage engines with lower compression, improperly adjusted valves, weak charging or glow plug systems, etc. can be harder to crank in cold conditions, and a slightly less viscous oil can aid in starting.
So it’s very much dependent upon your use cases for cold start ambient conditions, short trips, etc. the protection of 15w-40 vs 5w-40 will be the same at temperature.
I’d be more concerned about valve adjustments and keeping the battery charged (the alternators on these cars are lower rated and charge slower than modern cars), over pushing the 5w-40. Nothing wrong with using it. I have, and I do in some of my classic diesels, but not all of them and not all the time.
The super tech synthetic 15w-40 looks very interesting for these engines and the 60x series.
Daimler recommended the following for the OM61x series engines:
This chart I think was newer. CCMC G5 was a precursor to some of the ACEA ratings but implied more robust oils.
Folks recommend 5w-40 because older, high mileage engines with lower compression, improperly adjusted valves, weak charging or glow plug systems, etc. can be harder to crank in cold conditions, and a slightly less viscous oil can aid in starting.
So it’s very much dependent upon your use cases for cold start ambient conditions, short trips, etc. the protection of 15w-40 vs 5w-40 will be the same at temperature.
I’d be more concerned about valve adjustments and keeping the battery charged (the alternators on these cars are lower rated and charge slower than modern cars), over pushing the 5w-40. Nothing wrong with using it. I have, and I do in some of my classic diesels, but not all of them and not all the time.
The super tech synthetic 15w-40 looks very interesting for these engines and the 60x series.
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