Best oil weight for a high-mile MB inline-6?

[opposite_locker]

We have 240k miles on a '97 e320 (m104 gasoline inline-6) and I am trying to decide whether to move to a thicker oil. Car has seen Mobil 1 since the beginning with 7500-10k mile OCI (10w30 for first 150k, 0w40 since) and has always run flawlessly. I've recently noticed some oil seeping at the timing cover and at the back of the cylinder head, both of which are common issues for this engine. It isn't leaking much...just enough to leave a couple drops on the ground when parked overnight.

I was thinking of going with a thicker weight oil to minimize oil seepage and make up for any looser tolerances the engine may have after almost 1/4 million miles. I see no reason to switch from Mobil 1 since it has worked very well for the engine thus far.

Question is...which weight?

Mobil 1 15w50
Mobil 1 10w40 "high mileage"
Mobil 1 5w40 turbo diesel
Mobil Delvac 1 5w40

 

[charbaby]

Are you adding any make up oil between oil chances? If not, I see no reason for any change in oil grade what so ever and you may want to first take care of the leaks instead of moving to a heavier weight oil or High Mileage oil. Otherwise keep doing what your doing.

 

[Hethaerto]

Yeah, what he ^ said, just repair the leaks.

 

[tig1]

Sounds like the oil works well for you,keep it up. I do agree also about fixing the leak. This engine may run another 200,000 miles.

 

[ChiTDI]

240k? If it runs that well, repair cost would be a small price to pay for more of the same.
If you did switch, the 5w40 would be my hoice. Mobil 1 Turbo Diesel Truck or Delvac.

 

[Johnny]

I agree with both post above. The rear leak you see is probably coming from the back of the valve cover. I would have the valve cover gasket and the timing cover gasket replaced. That would also give you a chance to see what kind of deposits, if any are there. The Mobil 1 0W-40 is a very good oil and meets you MB specs. If I were going to use any of the above listed oils it would be the Mobil 1 5W-40 Turbo Diesel. I would see absolutely no reason to go to the 15W-50. I hope Doug Hillary sees this post as he has a great amount of MB experience.

Nice car.

 

[Drivebelt]

I don't think moving to a heavier 50 weight oil will make any difference for the leaks.

I would actually change to a different oil. It's not that Mobil 1 is a bad oil, it's just that some of their grades, like the 0W-40 will be made from a heavy concentration of PAO's (Grp IV) which can tend to shrink some seals over time. This is usually counteracted with esters (swell seals) but your mileage may vary. The lighter grades like 5w30 and 10w30 may use a fair amount of Group III base oils, so they may not be as hard on seals as the 0W-40. So you "may" have made the situation worse on your seals by moving to the 0W-40.

Couple of options.

1) Try one of the HM (high mileage) oils like Valvoline Maxlife. Even the synthetic-blend Valvoline MaxLife 5w30 has proven to be a very good oil (I think it will give many synthetics a run for the money). This would be my first choice.

2) Try a Group III based synthetic. In the 30 weight category, you could try Pennzoil Platinum, Quaker State. In the 40 weight Group III synthetic category, oils like Rotella T 5W-40 or Delo 400 5W-40 would be an option.

 

[opposite_locker]

Engine is not leaking enough to warrant any repair at the moment, and I do not have to add any oil between 7500 mile OCI's. The drips are more of an annoyance, and I was thinking a thicker oil might slow them down a bit.

I still definitely want to stay with Mobil 1, only because thet's what the car had been fed since it's very first oil change. What would the differences be between the Mobil 1 5w40 TD/Delvac and 0w40, other than the viscosity when cold?

Not to stir up another topic, but I thought Mobil 1 used only Grp IV base stocks...since when did they start using Grp III?

Thanks all for the input.

 

[addyguy]

All the oils you listed, including the one you are using, are great oils, and will all work well.

You might want to try the 10W-40 High Mileage to 'see' if it will slow or stop the leak you have.

 

[Drivebelt]

Quote:
Not to stir up another topic, but I thought Mobil 1 used only Grp IV base stocks...since when did they start using Grp III?


Mobil 1 uses Group IV, but according to the Mobil Japan site, almost all of the Mobil 1 synthetic oils are listed as having Group III content. They are listed as … PAO + catalytically processed. Catalytically processed means Group III. So, almost all Mobil 1 oils are a blend of Group III/PAO (and perhaps some Group V ester). The only Mobil 1 oil that is listed as PAO only is the 0W-40. The lighter grades like 5w30 and 10w30 probably use more Group III than some of the other oils with more demanding viscosity spreads.

See … Mobil.pdf … (5.1MB).

 

[opposite_locker]

Is there any difference between Mobil 1 Turbo Diesel Truck 5w40 and Mobil Delvac 1 5w40? I'm going to try one of the 5w40 Mobil 1 diesel oils or the Mobil 1 10w40 HM, depending on which I can find on sale at a decent price. This stuff has become way too expensive!

Thanks guys for the input.

 

[OVERKILL]

Mobil 1 Turbo Diesel Truck is normally cheaper, at least in Canada, but that is only because we can buy it in 5L jugs at Walmart......

 

[Audi Junkie]

MaxLife 10w-40 or Pennzoil 10w40 in your climate.

 

[berlyn]

Hi opposite_locker,
very nice ride!
Listen to me and the other guys here in the forum and repair the leak.
We hear and we read everyday about the reaction between the oil type group and the seals between the parts of the engine and this is true but the a seal is long gone if it allows every night 2 drops of oil to come out in your car.
I don't want to look like I am overreacting or being overprotecting but sooner or later 2 drops will be three, four etc..
If something isn't broken don't fix it and the opposite also,same applies with the oil also.
Be ahead of the game and fix it!!

 

[ChiTDI]

Originally Posted By: opposite_locker
Is there any difference between Mobil 1 Turbo Diesel Truck 5w40 and Mobil Delvac 1 5w40? I'm going to try one of the 5w40 Mobil 1 diesel oils or the Mobil 1 10w40 HM, depending on which I can find on sale at a decent price. This stuff has become way too expensive!

Thanks guys for the input.

They used to be identical, but now in the CJ formulation there are differences I'm told. In my case, the $ difference leads me to the Mobil 1 Turbo Diesel Truck. I think the D1 meets a few more specs, none which apply to me, nor perhaps to you.

 

[ChiTDI]

Originally Posted By: opposite_locker
Is there any difference between Mobil 1 Turbo Diesel Truck 5w40 and Mobil Delvac 1 5w40? I'm going to try one of the 5w40 Mobil 1 diesel oils or the Mobil 1 10w40 HM, depending on which I can find on sale at a decent price. This stuff has become way too expensive!

Thanks guys for the input.


Here is where the laundry comes clean:
http://www.bobistheoilguy.com/forums/ubb...&gonew=1#UNREAD

 

[opposite_locker]

Thanks!

No reason to repair the leak yet as I don't even have to add any makeup oil between 7500 mi OCI.

 

[Kestas]

I too have the M104 engine (95 E320). You must not be the original owner. The upper timing cover seal is a repetitive maintenance item. Mine's been changed twice already, and it's beginning to leak again with 83K miles.

It's silly to ignore changing the gasket and to deal with this problem via changing oil viscosity... especially when your oil regimen is working fine otherwise.

Oil leakage at the rear of the engine is also a common problem resulting from a head gasket leak. This too needs to be changed at repetitive intervals.

 

[HitManX]

I've got many older MBs, three I6 cars (OM603 Diesel, M110, M103)... 240k/5k on rering/265k accordingly.

The two gas versions are known for oil consumption and their leaks, cam boxes on the 2.8L, high RPM on the freeway wears the guides, etc. I agree with others, fix the issues and motor on. The bottom ends rarely fail and the heavier oil is not going to really do all that much. Outer seals are usually a quick day job, maybe two if you are really attentive on having a clean engine bay.

I used to be a fan of the /50s in these two (which was per the owners manual) and now I do a /40 after reading and asking around here. The M110 is on syn 0/40 and the M103 on 10/40. I will switch the M103 over to syn once I do the head rebuild this fall.

Oil has changed so much in the past 30 years or so, the very heavy weights just don't make sense at this point in time. The syn /30s outperform even the good dino /50s (initial oil flow/pressure, film sheer, high temp/rpm stability, etc) but since my clearances are so much looser on my motors than your M104, I stick with a slightly higher viscosity (the /40s), both conventional and synthetic.

Hopefully my ramblings helped.

 

[opposite_locker]

We bought the vehicle brand new in November '96 - HG has never been replaced, and I'm 99% sure timing cover gasket is also original, unless it was replaced at some point before the factory 4yr/50k warranty expired. I can currently see a bit of wetness on the block below both areas, but the seepage appears very minor. I think the later m104 had updated gaskets, so the leaks were less of a problem.

I'm beginning to think I should check lower down on the engine...perhaps oil pan gasket or rear main seal. Engine leaves 2 drops of oil when parked overnight, but leaves nothing if parked for 4 hours after being driven. I would think a timing cover gasket or HG leak would drip more after being driven than when cold.