gasoline @ 73

[Trond.N]

what kind of gas do i use on a 1973 450sl
where i live i got this options :
unlead 95 octane
unlead 97 octane
unlead 98 octane
super 98 octane
in 73 the 450 came with out catalyser i think should i then use the super 98 ?

[zeggate]

I don't believe 1973 450sl's had catalytic converters. I have one and there is no converter.

[Trond.N]

the car is from california
what kind of gas do u think it's supposed to use

[abe g]

I use regular in my 1977 450sl. Thats what the owners manual calls for. (octane about 87) Experets also add that regular starts easier than super. No knocks or pings with this use. If car knocks, check timing. good luck, Abe g

[Trond.N]

do i need to do some adjustments to the car

we got 95 octane as the lowest here in norway

[abe g]

95 octane should be fine with your car. the extra octane (over 87 rcommended) would be no problem. I assume that they charge more than if lower were available, and then again, possible not. If car runs without problems, stop worrying and enjoy. Abe G

[230/8]

Careful with your gasoline selection. I believe the numbers in europe are based on a different system. Ours uses an average of the RON and MON systems, so 87 should correspond to european 95. But, as engines age it may be wise to move up a notch to 97. Do europeans still use the 3 star, 4 star, 5 star system of gas grading at the pump?

230/8

[Trond.N]

no stars in my country

but i think this engine is so old that it is supposed to go on loaded fuel
and we dont got that anymore
do i need to put som stuff on insted of lead

[230/8]

If your car came from California then it should be fine to use unleaded gas. Most Mercedes Benz of that vintage and all newer cars have hard inserts for the valve seats which are fine with unleaded gas. Your first post indicated a "super 98 octane" and "unlead 98 octane." What is the difference? Perhaps the super contains lead or another additive for the valves of older engines?

230/8

[Trond.N]

yes the super 98 is with lead or additive
the regular is 98 unlead
on newer cars u can damage the cat if u use gas with lead in

[230/8]

Well then, the choice is yours to make. Your California version SL will run fine on one of the lower octane fuels without lead, but if you have any doubt about doing that, then you can use of the leaded gas to ensure your valve seats last the longest possible time, and the added octane will permit you to run it without worrying about engine knock from low octane fuel.

Good luck,

230/8