using too much oil? - PeachParts Mercedes-Benz Forum

lg4mat · #1 05-28-2007, 09:40 PM

I recently acquired a 1980 300d w/ 190K fully documented miles. The PO never missed an oil change. She either used 30wt. or 20/50 Castrol.
Well, I changed the oil as soon as I got it. I put in Rotella 15/40. Then drove 800 miles and had to add 1.5 qts.

Basically, thats a quart every 550 miles. The oil moved down the dipstick from top notch to lower. I am very disappointed with this. The car leaks virtually no oil and there is not a lot of blowby oil in air cleaner.

Will changing to heavier oil help?
If I change to 30wt. oil how much improvement should I expect?
I bought the car because of all the service records.
Am I missing something here?

The car is clean and in great shape I would like to keep it.

thatguy · #2 05-28-2007, 09:46 PM

15w40 should be perfectly fine unless you happen to live on the surface of the sun... How much blowby are you getting exactly in the air filter (i.e how soaked with oil is it?).

#3 05-28-2007, 09:48 PM

Keep it half way between the marks. It will use less oil there.

lg4mat · #4 05-28-2007, 09:49 PM

I should have mentioned that I live in Dallas area. Pretty hot most of the time. Air cleaner looks pretty clean. Really not much there at all.

lg4mat · #5 05-28-2007, 09:52 PM

I have not had the car long. Maybe a couple of thousand miles. Will 30wt. oil slow oil consumption? May add Lucas oil stabilizer.

300SD81 · #6 05-28-2007, 10:01 PM

How often did you check it? Could have been an air bubble or something, had it happen to me.. The car suddenly drank about a quart a little while after an oil change

lg4mat · #7 05-28-2007, 10:05 PM

I checked oil often. I have only had the car for 2000miles/5weeks. I am surprised that I am using this much oil given PO excellent care of car.

Palangi · #8 05-28-2007, 10:10 PM

PO may not have been using diesel rated oil. For example, I don't know of any diesel rated 20w50.

Sometime running synthetic oil for a while will help reduce oil consumption. Some say it frees up stuck rings.

lg4mat · #9 05-28-2007, 10:15 PM

She used Quaker State 30wt. for first 18 years. Then she used Castrol 20/50 after that. It is my understanding that 30wt was common in early years for these vehicles. A very experienced mechanic who only works on vintage Mercedes recommends I use 30wt now. What do you people think?

slarson80 · #10 05-28-2007, 10:23 PM

Quote:

Originally Posted by Palangi

PO may not have been using diesel rated oil. For example, I don't know of any diesel rated 20w50.

Sometime running synthetic oil for a while will help reduce oil consumption. Some say it frees up stuck rings.

I've been using Valvoline Duro Blend 20/50. It has a CF rating, my indy recommended 20w because my engine is tired. So far i"ve been pleased with the results. But it is about the only 20w I could find with a CF rating. Am I playing with fire? I've only put about 1k on it with this oil.

Sonny

Palangi · #11 05-28-2007, 10:36 PM

There are a few diesel rated 30 weights, Delo and Rotella for example. Even those are only rated to CF or CF4. The current 15W40's are all up to CH or CI nowadays. I dunno if the old QS oil was diesel rated, or if it still is nowadays. I haven't actually seen QS 30 weight in a while.

I am currently running Delo 30 in my 240D for the summer, but this will be the last fill of that oil, as it no longer carries CF4. I think these old engines with solid lifters need the zinc and phosphorus that CF4 represents. Going back to a 15W40.

Palangi · #12 05-28-2007, 10:41 PM

Quote:

Originally Posted by slarson80

I've been using Valvoline Duro Blend 20/50. It has a CF rating, my indy recommended 20w because my engine is tired. So far i"ve been pleased with the results. But it is about the only 20w I could find with a CF rating. Am I playing with fire? I've only put about 1k on it with this oil.

Well, what I have been reading lately is that you want at least CF4, mainly to prevent camshaft wear. One fill of some lesser oil is not poison however. I would just let it run its course and change it on schedule.

Towel Rail · #13 05-28-2007, 10:45 PM

Did the PO mention oil consumption? Perhaps it's always done this.

I can't think of any good reason to use 30 over 15W40. Rotella is good stuff.

- Scott

lg4mat · #14 05-28-2007, 10:51 PM

PO is with the Lord now. Family friend didn't say anything about oil consumption. Go figure. Just doesnt make sense with all the frequent oil changes that the car would be showing this much wear. Rings? Head job? I will drive it for a bit for now. But, I would like to fix the problem.

rrgrassi · #15 05-28-2007, 10:55 PM

Do you have all the records? Could be she took it to one of those quick lube places. When did you change the oil? How was the consumption prior to the oil change?

Using non diesel rated oil can cause excessive eingine wear, rings included.

How easy is the car to start? Could be leaky valve guides or worn out rings.

I live in between Rockwall and Greenville.