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1985 380SL
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Discussion Starter · #1 ·
I am new at this and I wanted to start with changing the oil and tune-up of my 1985 380SL. I think the oil drain plug is a 14mm hex drive. Am I right? Also, what metric size spark plug socket should I get to pull the plugs??

Thanks!
 

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You might want to put your location and car info in your profile. It helps to answer questions. I have my oil changed cause I hate to take the used oil for disposal so I don't know about the drain plug. My spark plugs are 13/16ths.
 

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Dugald said:
Is there such a thing as a metric plug?

The modern spark plug is an oddity where dimensions are concerned. 'Standard' wrench sizes of either 5/8 or 13/16 are universal for modern spark plugs. Yet the threaded portion is either 14mm or 18mm. How the metric with standard combination gained such universality I know not why.
 

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Outstanding Contributor , Bob's Your Uncle!
83 280 SL- 5 speed-The PIG
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The modern spark plug is an oddity where dimensions are concerned. 'Standard' wrench sizes of either 5/8 or 13/16 are universal for modern spark plugs. Yet the threaded portion is either 14mm or 18mm. How the metric with standard combination gained such universality I know not why.
It's a compromise between the Dimension Lords. God love the Canadian Gov't when they switched to Metric. I love owning two sets of tools. Times three tool boxes. Thankfully, my fourth box at Air Chaos only requires SAE.
 

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1982 380SL
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114 Posts
I think the oil drain plug is a 14mm hex drive. Am I right?

Thanks!
Yes, you need a 14mm hex driver for the oil drain plug. You can get them at Autozone, NAPA or SK HandTools.
 

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1985 380SL
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Discussion Starter · #7 ·
You might want to put your location and car info in your profile. It helps to answer questions. I have my oil changed cause I hate to take the used oil for disposal so I don't know about the drain plug. My spark plugs are 13/16ths.
Thanks, I will edit my profile. I see that spark plug sizes are English dimensions. I will try the 13/16", but it didn't seem to fit the first time around.
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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Thanks, I will edit my profile. I see that spark plug sizes are English dimensions. I will try the 13/16", but it didn't seem to fit the first time around.

I have two spark plug sockets - Big & Small - I use the Big one on the SL, so I guess it must be 5/8"
 

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1985 380SL
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Discussion Starter · #9 ·
Oil Plug

The modern spark plug is an oddity where dimensions are concerned. 'Standard' wrench sizes of either 5/8 or 13/16 are universal for modern spark plugs. Yet the threaded portion is either 14mm or 18mm. How the metric with standard combination gained such universality I know not why.

Thanks! This is helpful.
Any info on the drain plug hex size. 14mm??
 

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1986 560SL with M120 V12 Engine, 1988 560SL Stock
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Is there such a thing as a metric plug?
Thats a good question. The 380SL will use a 14mm threaded plug with a 13/16" hex socket. It must have been the Britts who invented this.

John Roncallo
 

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1979 280SL, 1984 280SL
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It's a compromise between the Dimension Lords. God love the Canadian Gov't when they switched to Metric. I love owning two sets of tools. Times three tool boxes. Thankfully, my fourth box at Air Chaos only requires SAE.
Nobby, in addition to inch and metric, I have a whole toolbox with nothing but British Standard, for my collection of Brit motorcycles. You don't even want to ask about thread sizes- the taps and dies will make your head swim. :surrender:

Chief
 
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