I switched my 81 380sl from 10W30 to 20W50 early this summer to reduce the smoke puffs that were coming from my exhaust on exit ramps, based on my belief that the smoke was coming from worn valve stem guides, and using a thicker oil would reduce the leaks.

In addition, my research indicated that many MB owners with older cars had switched from the specified 10W30 to 20W50 with no problems, and that a veteran tech named Marty, who answers MB questions on Just Answer, said that he used 20W50 in his 380sl here:
http://www.justanswer.com/mercedes/6votr-mercedes-benz-380sl-type-oil-does-m-b-use.html

Well, the 20W50 did reduce the smoking on exit ramps. But now I’m wondering if it the head gasket problem I just developed could possibly be related to using 20W50 -- even though, AFAIK, the 20W50 shouldn’t have increased the pressure on the head gasket, which I replaced less than 100k miles ago.

Any opinions on this would therefore be appreciated, especially as to whether I can continue driving the car with the oil leak.

DD

Can you describe how much oil is leaking?
Also curious if the timing chain was upgraded, not related of course (should have been single row chain originally I believe, and MB recommends upgrade to duplex chain)

__________________
Click here to see the items I have up for auction at EBay

Click here to see a photo album of my '62 Sprite Project Moneypit (Now Sold)

I really doubt if oil pressure will blow a gasket.One thing Mercedes doesn't do,that car engines used to be done.Was to retighten head gasket after 5,000 miles.

__________________
1999 w140, quit voting to old, and to old to fight, a god damned veteran

Oil thread.

The 20w50 will increase general oil pressure. The pump is working harder to move the thicker oil. It will take longer to heat up the oil to operating temp which is the only time the oil is actually sufficiently lubricating the engine.

If you changed brands of oil then there are additive features that should be considered but it likely an issue.

As an engine ages I would consider lowering the viscosity rather than raising it. As tolerances widen, you lose pressure. "Well I'll use thicker oil to fill the gaps."

That makes sense as far as keeping pressure up, but you don't need pressure, you need lubrication as fast as possible. A 0w30 will take far less time at startup to get to operating temp and the synthetics will cling to the parts that need.....

Sorry. Focus on OP Oil Leak question

Lets see a pic of the leak

Yes it's safe to drive as long as it continues to have oil in it. Slow leak is like an automatic oil changer with free undercarriage rust proofing, just stick a merc car diaper on it.

__________________

77' 300D, "Cartman" SOLD @ 150K (didn't know what I had)
83' 300SD, "The Superdon" 325k+ @ 28mpg
95 E320 wagon, "Millennium Falcon" 231k+ @ 24 Mpg
95 E300D, "Sherley" 308k @ 33.69 Mpg, currently anticipating a head
99 Suzuki Intruder "Trudy" @ 45 mpg

Oil doesn't cause head gasket leaks, loose bolts do. This is not an immediate problem. I would think that after a while the problem could go to water and or combustion chamber leaks which is bad.

__________________
85 300 SD ~ 115K
82 500 SEC Euro ??K
78 450SL 164K

Well, I did these head gaskets over 7 years ago, and they haven't given me a problem for at least 50k miles ago. Nevertheless, are you saying that I might be able to correct the leak by re-torquing the bolts to the specified 60NM or beyond?

DD

As I don't drive it that much, I haven't driven it enough to measure the oil consumption per mile yet. But if worse comes to worse, I suppose I could just add a quote or 2 as needed until I get the time and energy to change the gasket.

As for the timing chain, that was changed to a dual in the 80's, and I changed the chain and guides when I did the heads 7 years ago. So, they should still be fine. But thanks for asking.

DD

I would give it a try but leaks will remove some of the gasket material so it may not work. Lowest cost to try. Also possible that the head has warped a little and the only fix for that is resurfacing the head at a machine shop. This usually happens with sever overheating though. Did you re-torque the head a few thousand miles after the gasket replacement?

__________________
85 300 SD ~ 115K
82 500 SEC Euro ??K
78 450SL 164K

[QUOTE=thayer;3204925]Oil thread.

The 20w50 will increase general oil pressure. The pump is working harder to move the thicker oil. It will take longer to heat up the oil to operating temp which is the only time the oil is actually sufficiently lubricating the engine.
[QUOTE]

When cold the 20w50 is 20 weight which lubes very well for lower engine temp at start up. When the engine heats up the oil gets to 50 weight, thus 20w50 name.

__________________
85 300 SD ~ 115K
82 500 SEC Euro ??K
78 450SL 164K

The engine never overheated, and the manual said that re-torquing the head bolts after driving the car was "no longer necessary." However, the block is aluminum, and the bolt holes were heli-coiled when the heads were done 7 years ago to prevent the bolts from loosening up. So, now I'm wondering if one or more of the heli-coils may have loosened up and, if so, whether it would be possible to replace just those heli-coils without having to pull the head.

I also came across this Saab site, which stated that re-torquing all the bolts on two of its aluminum head engines to 90 degrees beyond the 60NM point would cure most head gasket leaks if the engines hadn't overheated. So, maybe there's hope there after all.

DD

Time to get out the wrenches.

__________________
85 300 SD ~ 115K
82 500 SEC Euro ??K
78 450SL 164K