I notice that having a problem with the ignition tumbler is a real problem. Considering that the key and the tumblers are steel might it be wise to put a little Mobile 1 on the key and work it around, or, is that asking for trouble?

Use graphite to lubricate the tumblers. Oil can goop up over time when/if dust is introduced.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

IMHO WD40 works best. Graphite powder will build up over time whereas excess WD40 can simply run out of the lock, and it does not get gooey over time.

-Jason

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

the best thing to use is nothing.

__________________
1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg

is the generally accepted lock lube - use sparingly and really only if you notice a problem with sticking (which you did in OP).

John in San Antonio

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John Hughes, was in Landstuhl, Germany but currently in San Antonio, TX


1978 280CE Astral Silver now 59,xxx miles and counting "Silber-Kugel"
1986 300E Black Pearl Metallic 143,xxx miles 5-spd daily driver w/ blk leather "Schwarz-Schönheit"
1989 190E 2.6 (euro) 5-spd Desert Taupe 112,xxx kms Had to leave behind in Germany!!! "Helga"
1983 300D Pastel Beige now 312,xxx + miles SOLD

OBK#24

Mercedes Part number 001 989 26 51 10 "Lock Cylinder Grease"

__________________
'84 300SD sold
124.128

As others have said, dry graphite is what is generally recommended as lock lube. I use it by blowing it into the lock with a small tube-applicator, run the key in and out and turn it a few times, then take compressed air and blow into the lock to blow out any excess graphite. That seems to work well for me. Just remember to wipe the key off before you put it in your pocket or you will have black stains from it on your hand, pants and anything else you touch!

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

I too use graphite. There is a risk of packing the tumbler with it and instantly jaming up the works, which is probably where all the horror stories come from. Apply sparingly and repeatedly until you get just enough in to lube the tumbler. Graphite doesn't attract dust and evaporate off the volatiles like oils do, both of which will create a sticky, gooey mess inside the tumbler.

With graphite, the tumbler gets stiff again because it dissipates over time. With oils, it happens because the goo builds up over time and needs thinning again. Graphite won't help with locks that freeze up in winter, but oils will. Pick your poison.

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'83 300DTurbo http://badges.fuelly.com/images/smallsig-us/318559.png

Broadband: more lies faster.

Okay, here goes.
A former (he has passed away) locksmith suggested using WD40 every now and again, never graphite.

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83 SD

84 CD