Greetings!
I'm new to this message board and I'm hoping to get some answers to some questions about my 1966 250 SE Coupe:
1. My owners manual mentions using gas with an Octane of 97 (although, it's a European import so I'm not sure if the #'s are the same over there as they are here). I've been using Sunoco 94 octane and adding lead substitute and fuel injection cleaner every time I fill up... Do you think I need to add lead? I remember hearing that lead helps provide cushioning for the valves... Also, what do you think about these fuel additives - Are they good or bad for my baby (I mean CAR!).
2. I was curious about what sort of oil I should be using.. My mechanic says I should try 20W50? I'm still not sure how to decode the oil ratings... I'm in upstate NY, where it gets cold as hell in winter (although, baby will be tucked into the garage).. I plan on driving the car up to the point where there's snow on the ground..
Thanks for your collective feedback (and patience with my weird questions!)
-Fredman, '66 250 SE/C (75,000 km)

I have a 63 220SEb cabriolet with a M127 engine and use Mobil One 10-30 and the local 92 Octane fuel. Although my car struggles on long upgrades, burdened with the weight of a convertible, I get no pinging. Since you have such a low mileage car with a later more powerful engine, I would think those choices would work out just fine on your coupe. Some say that Mobile One is too slippery for older engine gaskets and you may find seepage. I have not seen any increase in the 7 years since converting to my original never overhauled engine. Gregg

http://www.geocities.com/greggbambo/1963_MBZ_220_convt.html

I think you shouldn't need to add lead as MB has put hardened valve seats in their heads since late 50's early 60's. I believe they were the only company to do so.

I too add a fuel system cleaner, Red Line's Total Fuel System Cleaner. Good stuff. Not sure where you can get it in Ny, I get it at my local Pep Boy's for ~$5.00/bottle. You may be able to get it through PartsShop.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

Just be glad you don't live in California and subject to 91 Octane max. I use it in my 64 220SB which needs new valve guides and it seems to run fine.

I've heard that the newer synthetic oils are not good for the older gaskets and can cause them to breakdown. Not sure if it's true.