70-71 Oil filler cap finish?

[Shvegel]

I have been seeing a lot of high end restorations that have the later steel oil filler cap in yellow cad finish.  I am wondering if this is correct?  I purchased a NOS oil filler cap(not inexpensive)with the correct OEL stamping a while back and it came type 1(bright zinc).  I opened the original package.  I have looked online at a number of “original” cars but the ones with the yellow cad caps all seem to have undergone some underhood restoration before photos were taken can anyone shed some light here?

[MikeSimon]

Pat:

I wish I could be of more help...but anyway:

Here is a picture of the cap from my car 70/71 280SL. I know, there was some engine work done on the car, but I am only the 3rd owner and the filler cap is most probably still the original one. Don't think this was Yellow Cad.

[Shvegel]

Thanks for the picture Mike! Kind of what I think too.  A couple really low mile cars were sold in the last couple years and I think they “Spruced” up the plating and yellow cad plated the oil cap as well.  Once the pictures came out it became gospel but I think it might not be correct.

[MikeSimon]

I agree, Pat. this is an easy to replace item and it catches your eye right away when you open the hood and look at the engine. The original cap, even on a low mileage car, will show some signs of use. It will become really shiny where you "handle" it and some are sitting really tight, so hamfisted mechanics use tools to turn them and you see the marks.
I am sure, I have picture somewhere of a new car engine compartment which will also show the filler cap.

[ja17]

Yep, I vote silver.

[Iconic]

There is a little more info here starting with Reply #16:
https://www.sl113.org/forums/index.php?topic=24479.0

[Shvegel]

Thanks everyone!  My interest was peaked by a picture of a beaautifully restored 1970 280SL.  The cap was gold and other than that the car was flawless.  I just emailed the restorer and his reply was that they had a silver zinc plated cap for Concours use only.  The yellow zinc cap was for everyday use only.

[MikeSimon]

I do not remember the details anymore, but quite few years ago, many OEMs and suppliers around the world had to comply with government rules that outlawed certain plating processes. It affected us as a supplier of power steering pumps where we supplied stamped mounting brackets with the pumps.
Many of our brackets changed from a smooth silver to a blotchy yellow.
It is possible that we look at a similar scenario here, where the original plating became "politically incorrect" and the new one looked different.

[zoegrlh]

I have an original cap and it was and is silver and not yellow cad. A cap for show and one for go that the restorer has is a bit over the top. I show my SL in Concours one Cap, not a trailer baby.

[Shvegel]

I have a few bits I am saving for show since once they are gone that’s it.  Factory Beru wires with correct resistor ends, NOS distributor cap etc.

[Tom in seattle]

I read with interest the forum look back posted by Iconic.  Lots of discussion about the propriety of screw on caps vs later bayonet type.  I'm guessing the reason they changed, in part to the bayonet,  was that if the screw on cap was not screwed all the way down it was possible to dent the bonnet......I saw my PO do it.