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Old 08-06-2019, 09:06 PM   #25
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Default Re: Oil. Is this the real deal or ?? Major bullet points and concerns

Originally Posted by Bobnoxious View Post
A few Mercedes documents to consider.
Hi Bob,

I've been reading this thread to get the counter-arguments against Tom Stephens' advice. First off, thank you for providing your views on this. It's all useful information. What I'm struck by most is that first image you attached from the owners manual. Thank you for posting this. It makes three things clear:

1) If you idle a lot or do a lot of city driving (stop-go, short trips), you need to change your oil as often as every 3,100 miles due to fuel accretion into the engine oil. MB even has an error code to indicate high engine oil levels (HI) due to fuel accretion. That's it. Straight from MB. Anyone arguing against this overall truth is wrong. Period.

2) If you idle a lot or do a lot of city driving (stop-go, short trips) you will interrupt the proper functioning of the DPF. That's it. Straight from MB. Anyone arguing against this overall truth is wrong. Period.

With those established as truth, regardless of any blog post or comment by anyone in this or any other message board, we can then debate the solutions. You settled those points once and for all with that image from the manual. Thank you!

Others should accept them as truth, or at least realize they'll be contradicting their own owner's manual if they argue against them.

Now, regarding Tom Stephens. After reading the latest version of his web page, and calling and speaking to him for 1.5 hours, here is what I have concluded.

1) Tom is essentially saying the exact same things as stated in (1) and (2) above.

2) He goes further and says that not only do you need to change the oil more often, but you can take steps to reduce fuel accretion into the engine oil (higher viscosity oil), and you can take steps to reduce the damage that DPF interruption causes (catch tanks/EGR valve delete).

3) All of his suggestions are potential violations of the vehicles warranty if handled improperly, but not definite violations insofar as using different oils is concerned. See my next post below for the truth -- from the MB manual itself, on that. Some of his suggestions might be dated and if followed could damage a newer vehicle. Any person following them does so at their own risk.

Regarding the arguments for/against the two big ones, here's my take on those:

1) Fuel accretion into the engine oil. This problem is real, as MB tells us in the owner's manual. It's logical that the use of higher viscosity oil would result in a tighter seal on each combustion stroke (thin oil, thin seal, thick oil, thick seal). It's also logical that a better seal means less fuel accretion into the engine oil. Is it certain? Not that I've seen, but it sure is logical, and this idea isn't being discussed in a vacuum. It's being discussed in an environment of the established (1) and (2) issues, and with many people dealing with emissions system problems. Will it also void the warranty? Possibly, especially if you tell MB your'e doing it, because they may not trust that you're following their guidelines (see post below). But it should not if you stay within their guidelines. Will it result in other unforeseen damage? Not clear. I have no proof of any damage, but I do know at least one person who has been doing this for 2 years with no issues. That's not enough data though. Just a single anecdote.

Also, you'll note that MB is indeed using a low viscosity oil (Mobil 1), in part to keep fuel economy maximized. Mobil 1 touts those properties right on their website. I see plenty of arguments against using any oil besides MB's recommended Mobil 1 ESP (for newer sprinters), but that doesn't mean Tom is wrong about the advantages of high viscosity oil when you know you're going to idle a lot or do short trips in reasonable weather. It also doesn't mean you can't use other oils and still be within warranty (see post below). Tom was the first to tell me on the phone you can't apply one oil solution to all seasons and all driving conditions though.

2) The other steps he suggests are more drastic, but largely targeted at those who have already done some engine damage, are now in a downward spiral of continual emission systems replacements, or who have newer vehicles but plan to do a LOT of idling or stop-go/short trips. EGR delete/catch tank can be done by anyone, and there is again a logical reason to think this may help. It's designed to prevent unspent fuel mixed with soot (essentially exhaust) from being routed back into the the turbo. MB has to route it back in because they can't vent it into the atmosphere, per EPA. A catch tank just catches it, and makes about a dixie cup of sludge you drain every 2000-4000 miles, which would otherwise be routed back into the turbo. But again, it surely voids the warranty, so not for everyone, possibly not for anyone.

3) I have nothing but gratitude for all of the counter-arguments against Tom's advice. It's all good information to have. (Some of the snarky name calling by other members on this and other related threads, not so much). But for the real advice and counter arguments, and in particular for your posting of the image in the manual -- thank you Bob!

And finally this: for most people, it's wise to stick with the manual.



Last edited by mgladden2; 08-06-2019 at 10:20 PM.
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