How Much Coolant in Oil in Order to Be Visible? - Page 2 - PeachParts Mercedes-Benz Forum

shertex · #16 12-10-2010, 08:34 AM

Quote:

Originally Posted by Brian Carlton

Depending on the size of the leak and how frequent the oil changes, the glycol accumulation in the oil can potentially harm the bearings.

However, I do believe that this phenomenon is a bit overrated and the leak would have to be significant for this to occur.

I'm doing 10,000 mile oil changes with Mobil 1 TDT 5w40 and am losing about 1/4" of coolant every 1,000 miles.

Oil under valve cover and on dipstick is absolutely jet black....not a trace of anything else.

jdh122 · #17 12-10-2010, 08:36 AM

Shertex - You might recall that I chimed in pretty quickly when you first posted about your disappearing coolant issue, saying that I also was losing coolant, had the Blackstone oil analysis done on my car ('83 300D) and it came back showing 0.25% coolant content after 5,000 miles.

Since making that post I have called my mechanic (a very respected classic Benz specialist in Houston), described the issue and the oil analysis results and asked his opinion. After asking me to confirm that the oil was not "foamy" and otherwise looked normal, he suggested that I wait until the next oil change (another 5,000 or so miles), have another oil analysis done and see if the problem has gotten worse. I asked him point blank if continuing to drive the car without solving this problem could lead to issues now or down the road, and he said "not unless it gets a lot worse". This is from the mechanic who knows that he will get my business once it is time to do something about this issue (e.g. replace the head gasket).

So, at least in his opinion, whether your engine is at risk depends on the amount of coolant making its way in. If it is a small amount, it might not require immediate action and could permit a "wait and see" approach. I know that some people on this forum would advocate immediate action on this point, so it sounds like reasonable minds could disagree, but I thought you'd want to hear what at least my mechanic had to say.

Good luck with the oil analysis.

shertex · #18 12-10-2010, 08:40 AM

Quote:

Originally Posted by jdh122

Shertex - You might recall that I chimed in pretty quickly when you first posted about your disappearing coolant issue, saying that I also was losing coolant, had the Blackstone oil analysis done on my car ('83 300D) and it came back showing 0.25% coolant content after 5,000 miles.

Since making that post I have called my mechanic (a very respected classic Benz specialist in Houston), described the issue and the oil analysis results and asked his opinion. After asking me to confirm that the oil was not "foamy" and otherwise looked normal, he suggested that I wait until the next oil change (another 5,000 or so miles), have another oil analysis done and see if the problem has gotten worse. I asked him point blank if continuing to drive the car without solving this problem could lead to issues now or down the road, and he said "not unless it gets a lot worse". This is from the mechanic who knows that he will get my business once it is time to do something about this issue (e.g. replace the head gasket).

So, at least in his opinion, whether your engine is at risk depends on the amount of coolant making its way in. If it is a small amount, it might not require immediate action and could permit a "wait and see" approach. I know that some people on this forum would advocate immediate action on this point, so it sounds like reasonable minds could disagree, but I thought you'd want to hear what at least my mechanic had to say.

Good luck with the oil analysis.

That's very helpful...and encouraging.

As I mentioned, I am losing coolant at the rate of 1/4" of expansion tank level every 1,000 miles. How does that compare to your situation?

Brian Carlton · #19 12-10-2010, 08:43 AM

Quote:

Originally Posted by shertex

I'm doing 10,000 mile oil changes with Mobil 1 TDT 5w40 and am losing about 1/4" of coolant every 1,000 miles.

Oil under valve cover and on dipstick is absolutely jet black....not a trace of anything else.

The '86 SDL also loses a bit of coolant that I've never been able to find. It loses slightly more than 1/4" every 1000 miles. The oil analysis never shows any glycol but it does show sodium.

I'm not pulling the head.

shertex · #20 12-10-2010, 08:47 AM

Quote:

Originally Posted by Brian Carlton

The '86 SDL also loses a bit of coolant that I've never been able to find. It loses slightly more than 1/4" every 1000 miles. The oil analysis never shows any glycol but it does show sodium.

I'm not pulling the head.

That's interesting for a couple of reasons, most notably the fact that you've never been able to find the leak. As much as I want to keep the car forever, I'm more and more thinking that this may end up being a gremlin I just learn to live with.

jdh122 · #21 12-10-2010, 08:51 AM

Quote:

Originally Posted by shertex

As I mentioned, I am losing coolant at the rate of 1/4" of expansion tank level every 1,000 miles. How does that compare to your situation?

For whatever reason I haven't actually measured, but it's VERY slow.

shertex · #22 12-10-2010, 08:55 AM

Something else I wonder about: I wonder if the quality of the oil has any bearing on the degree to which the system can handle coolant in the oil. May be an additional reason to use an extremely high quality oil.

Brian Carlton · #23 12-10-2010, 09:09 AM

Quote:

Originally Posted by shertex

Something else I wonder about: I wonder if the quality of the oil has any bearing on the degree to which the system can handle coolant in the oil. May be an additional reason to use an extremely high quality oil.

I think not. Oil will simply disperse whatever glycol you've got to a point where the concentration isn't damaging, provided that the leak is not massive. Any oil will do the job. Our eight quart systems are obviously superior to the five quart American vehicles, simply because we've got more oil for dispersion.

I do think that using dino oil and changing every 3K is probably the better choice if glycol is confirmed in the oil. A better synthetic going 6K will have twice the glycol concentration by the time you change it.

Oldwolf · #24 12-10-2010, 09:19 AM

Is the coolant loss the same during the winter?

I've wondered how a reservoir cap lid that lets the system pressure go too low will effect evaporation. Summer coolant temps are higher, so maybe more loss (evaporation) during that season. What shape is your reservoir cap?

tobybul · #25 12-10-2010, 10:49 AM

when u do an oil analysis, if there is coolant in the oil indicated by abnormally high sodium, the next indicator is high lead content which indicates metal wear usually from bearings due to coolant dilution in the oil.

If both are above normal level, Blackstone says there's coolant contamination.

vstech · #26 12-10-2010, 11:06 AM

does the SDL have the overflow return tank and line like the 124 does? could it be shooting some out, and not sucking it back? is the overflow line intact?

shertex · #27 12-10-2010, 01:11 PM

Quote:

Originally Posted by Oldwolf

Is the coolant loss the same during the winter?

I've wondered how a reservoir cap lid that lets the system pressure go too low will effect evaporation. Summer coolant temps are higher, so maybe more loss (evaporation) during that season. What shape is your reservoir cap?

My reservoir cap visibly looks in great shape (though I realize it could still be compromised) and is seven years old.

shertex · #28 12-10-2010, 01:13 PM

Quote:

Originally Posted by Oldwolf

Is the coolant loss the same during the winter?

Not sure yet....the rate has slowed, but I'm thinking that may be because of a lower beginning level (I've been suspecting the overflow system).

tobybul · #29 12-10-2010, 01:24 PM

head gasket issues are difficult to diagnose until the obvious occurs. What i have learned however (from the symptoms on my 99 Taurus) is that consistent coolant loss for no obvious reason will most likely lead to a head gasket issue.

I had coolant loss on the Taurus for about 3 years. I changed radiator and water pump thinking those were the causes but still continued to loss coolant. The car ran well. Finally, the gasket gave way and the car died (I was able to limp along enough to get it close to home). Ended up donating it to a Career tech Center for them to work on.

My C220 that has 312k miles has also been lossing coolant for some time. Still rans well but I have it parked now getting ready for a head job that I plan to diy

.

shertex · #30 12-10-2010, 01:27 PM

If my expansion tank cap has gone seven years and 85,000 miles, should I just replace it anyway even though it LOOKS to be in great shape? I guess it's worth spending ten bucks just to eliminate a possibility.

How long do you typically go before replacing yours?