I'm a believer in additives for my 35D
 

I've never been a fan of fuel or oil additives but I've become a big believer after my recent experience.

I bought a 2009 X35D and have driven it the last 50000 miles. At 88,000 miles I added 8 oz of Seafoam to the crankcase and the remainder of my open can to the diesel tank. I did it before a round trip of about 1700 miles.

MY Mileage has gone through the roof,

For two years I would average about 21-22mpg on my work commute and any extended freeway driving I'd average 23 and maybe 24mpg on occasion.

After Seafoam, Im getting over 30mpg. I just did a 500 mile trip where I averaged 32.6. My work commute for the past month has been 28.5 and higher. It's not just a certain stretch of road. I've made these same trips for two years but with much lower results. The only change is the Seafoam addition.

I'm a believer now and will add a can near each oil change.

SeaFoam has come up on the Jukebox here, before...

No arm wrestle: if you like it/works for you, good.

Some other views and opins on using that product in modern engines pasted below, but maybe your diesel is different or more receptive. ;)
GL, mD

Post #7, and others in this thread:
http://www.xoutpost.com/bmw-sav-foru...additives.html

http://www.xoutpost.com/bmw-sav-foru...v-seafoam.html

http://www.xoutpost.com/bmw-sav-foru...4-engines.html

A couple of thoughts.
If seafoam will burn in a diesel straight out of the can, I wouldn't add it to the oil in a modern engine. All you are doing is reducing the viscosity of the oil- keep in mind there is high stress on the oil and internals of today's engines. It not your father's mid 80's Mercedes diesel.

The owners manual specifically says don't use additives.

I don't see anywhere on Seafoam's site where it talks about impact on the SCR or Catalyst on today's diesels. Maybe I missed it?

Are you relying on your dash for mileage calculations or fill tank and divide manually? I've never seen a mystery oil that will add 30% in 500 miles. Or 20% or 10%.

Old Mercedes diesel engine will typically have a compression ratio over 20:1. Older ones came with a mechanical oil pressure gauge-if the pressure drops under 45 psi (at idle) your engine has some wear. If it dips under 30 psi, it is having serious problems. M57N2 in our diesel X5s come with ~ 16:1 CR and will probably get away with half of the old Mercedes oil pressures. Just as an example, the new Mazda Skyactive gasoline engines come in compression ratios of up to 14.5:1.
On your other points I agree :thumbup:

23mpg Diesel engine on highway? Now I feel much better about my car that gets 24-25.
In town is more like 18-19

Mine averages 21 mpg mixed, with my at times idiotic driving and flooring the pedal for more than a few seconds(this is with est 450/550 ;)). 50i with probably similar acceleration is not probable to do better than 15mpg mixed. Last year i drove a 50i without exhaust(very, very addictive I must say) for a few days in our neighborhood and it hardly got 12 :D

I like using Sea Foam because of the smoke show but I'm leery of using it on my BMWs. Mine run great as they are and I get great mileage as they are. I just don't want to mess with them in that way I guess. Could it make a difference on vehicles that are already hurting? Well, maybe it does.

just saw this while browsing YouTube, what are the thought?

https://www.youtube.com/watch?v=pAJSOsIbqyc

I like it and I've always been a believer. I've been driving diesel Mercedes for the past 20 years. This is the first time I bought an X5 diesel.