My 1986 Mercedes 300E (gas inline 6) with 125,000 miles is consuming a quart of oil every 600 miles. There is no smoke, barely leaks any, it has great power and runs like new. How far outside of normal consumption do you guys think this is and how much worse is it likely to get? I'm running conventional 10w-40. Thanks for any info.

 

I cant offer any experience with that particular engine but, any engine I have ever had that used that much oil ( actually never had one use that much )definitely showed it! No doubt if it was burning it or leaking it. I had a chevy 250 inline 6 that burned a couple of quarts (half your consumption) every oil change and it showed lots of blue smoke when compressioning down hills (valve seals) and when starting cold. Wish I could help?

 

I got to check what oil I'm running on my gas Merc....A bit high at a quart ever 600 miles....Does it smoke blue when started cold??Those Merc diesel is one heck of a motor...

 

My ram 2500 with a 360 use to burn a quart every 1000 miles. No smoke or any unusual running problems. Found out it whe nthe intake plenunm leaking, got it fixed and never had a problem again with oil consumption. I dunno how your mercedes engine is but maybe is using oil that way.

 

I hear this engine uses oil but this seems to be excessive. No leaks, no smoke, nothing. The low oil light comes on every 600-700 miles and I dump a quart in (it is down). I have been driving it on I-5 a lot at 80MPH (3700+RPM continuous). Could that have anything to do with it?

 

Is this engine overhead cam?If so I have seen the wrong PVC valve installed and cause oil consumption.

 

Your in Cal. , put in thicker oil , 15/40w , check the PCV like mentioned above .
Valve guide seals are another common oil consumption spot .
Do a leak down test to see where the oil is going .
If you have a cat , that would burn the oil , not allowing for exhaust smoke .

 

Thanks for the advice. I just did some searching on the internet and apparently they use more oil when filled to "max" on the dipstick. I'll keep in in the middle for a while and see how it goes.

 

I would say 1 qt per 600 miles is about 1 quart too much.

I have 140K on my frontier with no noticeable oil consumption every 10K.

 

It isn't a Nissan.

 

surely that fine german engineering has to be better than that Jap junk...

 

3700 rpm will increase oil consumption over 2000 rpm. I would suspect valve guides or seals though. What kind of oil are you using? Sometimes a good synthetic will help slow down oil consumption. The PCV or CCV depending on which one it has is something to look at also.

 

Try a high mileage oil, they put additives in them to make seals swell to aid in retarding oil consumption. Valvoline and Castrol make high mileage oils that come in different weights.



Tim

 

Thanks for the tips. I'm using Valvoline 10-40. I'm scared of synthetic after it caused leaks in my last run with a beater. A coworker suggested running diesel 15-40. Is that good or bad advice?

 

I run 15/40 in everything including my Honda generator. Remember as they thin the oil to get better mileage standards, the heavy diesels have to keep the viscosity intact.