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.
