Trying to understand which oil to use for Mercedes

[tewiser]

Hi,
Having the M256.9 engine, and the manufacture suggests to use any of the following specs:
229.51, 229.52, 229.61, 229.71, 72.

From my understanding, .51/.52 are a bit older and it contains several viscosity: 0w30/5w30/0w40, etc.
https://operatingfluids.mercedes-benz.com/sheet/229.52/en

The .71 and .72 is newer and more lighter weight for less gas consumption. It only has 0w20.
https://operatingfluids.mercedes-benz.com/sheet/229.71/en

From the lubrizol, it looks like .71/72 has everything better than .51/52, including wear.

So is it safe to say, using 71/72 oil is better than 51/52 in every aspect? (mobil 1 esp 0w20 is same price as 0w30)

 

[Jetronic]

no, it's not safe to say that.

the older oils needed to get a C- to pass, and now the passing grade is C+.... is a good analogy. the specs define minimum standards, but how well any oil that passed did, is a secret. you might get a C+ or an A- oil...

 

[kschachn]

You’re really struggling with fluids for this Mercedes.

Use any of the allowed approvals. If you want to reduce wear a bit then use one with a higher HT/HS.

 

[tewiser]

You’re really struggling with fluids for this Mercedes.

Use any of the allowed approvals. If you want to reduce wear a bit then use one with a higher HT/HS.

thank you.
On automotive engineering classes these days, and been in way too many discussion in class on every tiny bit of these things.. trying to get fact straight not listening to nerds.

 

[dubber09]

Basically, if you are after little better fuel economy - then .72; if you are after better engine protection, run higher RPMs and longish oil change intervals - then .52.

 

[BMWTurboDzl]

Hi,
Having the M256.9 engine, and the manufacture suggests to use any of the following specs:
229.51, 229.52, 229.61, 229.71, 72.

From my understanding, .51/.52 are a bit older and it contains several viscosity: 0w30/5w30/0w40, etc.
https://operatingfluids.mercedes-benz.com/sheet/229.52/en

The .71 and .72 is newer and more lighter weight for less gas consumption. It only has 0w20.
https://operatingfluids.mercedes-benz.com/sheet/229.71/en

From the lubrizol, it looks like .71/72 has everything better than .51/52, including wear.

So is it safe to say, using 71/72 oil is better than 51/52 in every aspect? (mobil 1 esp 0w20 is same price as 0w30)

The Germans, in part, arrange their oil approvals by hths rather than "good, better, or best". So in your case 229.51/.52 can ONLY be 30 grade or higher because the min HTHS is 3.5cP and 229.71/.72 conversely can ONLY be 20 grade. Now it's true that .51/52 are an older spec but that's only because Mercedes didn't get into the 20 grades until around 2015. They'll also periodically update their approvals for example a LSPI test was added to all their approvals beginning around 2019.