I don't normally use Loctite unless the locating really demands it. You certainly can try it if you're concerned. The heat is not excessive.

Since I still believe that 3000 miles is a good time to change oil, I'll probably stick to dino oil.

What's the best dino oil for a 1984 MBZ 300D Turbo?

And should it be 5/40w?

Thanks

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1984 300D Turbo

I forgot to state that the temps outside now range between 45F and 70F.

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1984 300D Turbo

Delo 400, Delvac 1500, or Rotella are all good choices. The weight is 15W-40 which is a bit too heavy for winter starts..........the reason to stick with one of the synthetics.

Wikipedia:

[edit] Synthetic Base Stocks
Synthetic motor oils have been made from the following classes of lubricants:

Polyalphaolefin (PAO) = American Petroleum Institute (API) Group IV base oil
Synthetic esters, etc = API Group V base oils (non-PAO synthetics, including diesters, polyolesters, alklylated napthlenes, alkyklated benzenes, etc.)
Hydrocracked/Hydroisomerized = API Group III base oils. Chevron, Shell, and other petrochemical companies developed processes involving catalytic conversion of feed stocks under pressure in the presence of hydrogen into high quality mineral lubricating oil. In 2005 production of GTL (Gas-to-liquid) Group III base stocks began. The best of these perform much like polyalphaolefin. Group III base stocks are considered synthetic motor oil in North America.[2]

Now, depending on your situation, describe "better". Warm climate with extended run periods and you likely won't see much of a difference. Cool climate with short run periods and the "synthetic" will usually win out due to its flow characteristics. All in all, there is no magic oil, regardless of what that mechanic tells you.

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Sam

84 300SD 350K+ miles ( Blue Belle )

Agreed, 15W40 is best and will start well down to 25*F in my chart on the bottle. 5W40 is only really recommended for temps at 10*F and less. You should be fine with 15W40 now and Rotella is a good one.

All diesel engine oil should be "C" rated followed by a second set of letters and numbers, such as "CH-4/CI-4". The higher C rating, the better oil protection and resistance to oil burn off as well as avoiding dry starts!

I also add Lucas Viscosity improver and this has made my engine idle a little faster slightly and my oil pressure at idle a little higher. Less engine noise after sitting for several days also would tell me it helps to cling to metal parts and avoid dry starts.

Mobil makes some "full syn" oils: the turbodiesel & truck, Delvac 1, and one I believe they call extended mileage or similar (a gas-engine oil).

The RedLine synthetic is a polyolester base, better and more expensive than the Amsoil and Mobil 1, not just a Mobil re-brand.

Amsoil also sells full-syn, groupl III, and blended "synthetic" oils as do several other oil companies such as Castrol and ELF.

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Gone to the dark side

- Jeff

Someday when I have more money I may do that, but as a college student, I can't afford to blow the $25 it costs to have the oil analysis done...that money is better spent on the car itself.

btw, I am an engine whisperer....I understand them and they understand me

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Exactly, I figure a 4k change is way better.

I drained the last of our M1 oil out of the '83SD yesterday, it had 4,900 on the oil and it wasn't as thick as when I drained mine at the same miles....maybe my engine makes more soot. Either way, its also on Rotella Syn + 4k change now. So now all our cars are on the same oil. If we buy the 240d we've been looking at....that one will be changed over to it as well.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I just use Delvac 1 and change it every 6 months. That works out to somewhere between 3-4 thousand miles.

603's have loud lifters, they really like clean oil.

Synthetic is nice because it isn't really affected by temperature, so at 0 your engine will spin over much, much faster. I honestly don't see the point of using 15w40 in the winter when you can get that Rotella 5w40 so cheap. Unless you just enjoy hearing that engine turn over nice and slow. Or during the summer because Rotella 5w40 is rated for year round use.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200