Do the 86' 420SEL use regular gasoline?
 

I have been looking at a few 1986-88 420SEL's and happened to notice that the 86' models do not say "premium unleaded fuel only" like the 87' and newer models do. So I am wondering if regular fuel can be used in the 86' models, or did they just decide to add that to the instrument panels on the 87'+ models and elsewhere on the 86' models?

Thanks in advance.

John Baker
 

I have an 83 model 380SEL and it takes premium unleaded so Im sure your 420 would also.:o

My 380SE uses regular 87 octane.

Starting in 1986 all MB gas engines in the USA required 91 octane EXCEPT the 190E 2.3 8 valve! 1987 on ALL MB gas engines in the USA require 91 octane.

I'm 90% sure you are paying too much for fuel. The fuel gauge in the inst cluster shouldn't say premium only. There should be a little aluminum stick on sticker on the left side of the dash that says UNLEADED FUEL ONLY.

Thanks guys. I also went to look at other 86' models on the internet and they do not say "premium only", but the 87's do. I guess this was something that they added for 87'.

Thanks again.

I'm not in the car right now but I'm positive our '86 420SEL says "premium unleaded only".

Checking one of the few books that came with the car (originally sold in California), on page 12 of the Maintenance Booklet for gas engines it says the 190 E 2.3 can use unleaded with an anti-knock index of at least 87 while all other models should use only premium unleaded with an anti-knock index of at least 91. It goes on to say engine damage could occur if premium fuel is not used and refers back to the Owner's Manual for special precautions (sorry, didn't get that book with the car...).

Gas question 560sl
 

I have a 1986 560sl amd there is a sticker right near the gas guage that states "use premium unleaded gas only" and mine was a direct import from Germany.

my 84
 

500sec uses regular.

tom w

I have been driving my '86 560 SEL since new, now with close to 150K on the clock, and use only regular unleaded fuel. As long as you are not doing a lot of high performance driving or experiencing any engine knocking you shouldn't have a problem. Others on this board say they get better mileage using premium but I don't think it is worth the extra 20 cents per gallon. My '86 averages 15/16 city and 18/20 mpg hiway at 70mph.