Main.TrailIndexPage | Fuel System | Fuel This section describes Fuel used by the Mercedes-Benz 230SL, 250SL, 280SL.

This component is part of Fuel Systems.

Definition

Fuel (Gas, Petrol, German: Benzin) is what drives the car. The following topics are described in this section.

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Leaded or unleaded

I just received an original owner's manual from the Classic Center. It says to use high octane fuel and specifies some European octane rating. I assume it would be leaded fuel since it's a 1966 book. My car's previous owner says he used regular 87 octane unleaded and put a lead additive in it. He supplied me some of this additive and I have continued to use it with regular 87. What fuel do all of you use in your Pagodas?

Will Samples says: the cheap stuff until the engine starts to ping real bad, then I check the timing and if needed step up a grade. So far I have been able to advance the timing about 3 degrees past the factory setting and gone up a grade in fuel. But, if you have a stock ignition setting, the cheap stuff should be ok. You do not need a lead substitute. The lead is supposed to prevent valve seat recession. But Mercedes valve seats were always hard enough to not need the lead. Remember, the lead is introduced to the valve and seat thru the intake runners in the head. Therefore covering the valve face and seat. But the 300 SL Gullwing and Roadster had fuel injection directly into the combustion chamber, the lead in the gas not physically going over the valve and seat. And those cars were started in 1955. If there was ever going to be a problem with them not getting lead where they needed it, it would have shown up before the 113's were made. Mercedes was way ahead of the pack when they did these cars. No need for lead in the gas then, no need for it now.

My 1967 Euro-spec 230 SL has been running unleaded for the 25 years that it has been in the US, and it hasn't affected it in the slightest. It uses 92 octane premium. Everything that I've heard about leaded-vs-unleaded gas has indicated that unleaded gas doesn't adversely affect Mercedes engines, and you shouldn't bother with the lead substitute.

Achim adds: up to the seventies and later Mercedes-Benz used valve seats made from iron which are "weak." From the 80-ies on they have been using valve seats made from steel which are "harder." In Germany leaded fuel was discontinued several years ago. Many owners of old cars were concerned and asked the same questions as you did. Mercedes-Benz released several public statements in journals, on request and in the shops. They all say the same. You can run the car without any substitute additives. Mercedes even warned of any additives. You shouldn't use anything (to "clean" the valves, etc.). However, Mercedes-Benz recommends to check the free play of the valves twice as often as the normal intervals mentioned in their original technical manuals (owner's manual, shop manual, tables manual) and to adjust it if necessary. There is no need to exchange the valve seats. If you want to do that anyway (during an engine overhaul or so), we were told that Mercedes-Benz today only sells replacements which are made of steel.

I'm curious as to what everyone is feeding their cars. The owner's manual calls for (gulp) 96 octane. Unless they changed the octane measurement scale, that is simply not commonly available everywhere (though I do have my choices of racing fuel suppliers locally). Here as elsewhere I'm assuming 92 octane premium is about the highest standard. Everyone using this to their satisfaction? Are you adding "octane booster" or straight up? Any additional comments?

I have a 1969 280SL and I'm using 93 octane from my local station. It works extremely well with the timing set to 5š BTDC.

There are different measures for the octane rating. US 91 represents about 95 European. I am using 91 in California without any problems - even on my 300SEL 6.3 that calls for Euro 98. No need for additives.

As regards fuel, I was told by (should be very) knowledgeable mechanics that the Pagoda engines are capable of running on unleaded without harm, due to the way the valves/seats have been manufactured. I don't know for sure whether this is true, but I was told by at least two experts independent from each other. I would not go blind on a regular MB dealer really knowing these ins and outs of 30+ year old cars.

I second the motion. I've been told by several good sources independently that there is no need for lead. Just use higher octane unleaded fuel.

MB supposedly used hardened valve seats from 1963 on.

Pete Lesler: Been running unleaded 91-93 octane for about 10 years or more. No evidence of valve recession or any other malady.

David Seidman: my 1969 280SL has been running most of its life on unleaded fuel - leaded has not been available here in the US for nearly 20 years (to my memory). I seem to remember that when we still had leaded fuel, the spark plugs would get fouled up and require a "wringing out" (3rd gear, under open throttle on the highway, running up to @ 6000 RPM to clean them off [aka an "Italian tune-up]). I must honestly say that I do not miss the lead one bit and I get fine performance from my car - and have for @ 160,000 miles! Happy lead-free motoring.

This issue comes again and again. The MB Classic Center people say it is more than fine to use unleaded for our cars.

Takes 3 to 4 attempts befor she spurts to life. Then all is fine. When I turn off the ignition, she gives a last splutter before giving up with a shudder. Any comments welcome. Did US model cars 280SL 1969/70/71 use unleaded or leaded gas in view of the cars having been modified to meet US reglations. I am using unleaded 95 with a common additive that cars that used to use super have to add. What is the best fuel mixture?

I am pretty sure that all W113's can run on unleaded fuel without any modification. I run premium (super) unleaded, i.e. 98 octane. As far as I am aware, the US models did not have anything standard that on euro models was optional. They did have some added features like emission controls, side marker and sealed-beam lights and bumper guards (from some point in time on) but, to my knowledge, all options available in Europe had to be ordered special in the US as well. Am I right group?

I used Amoco Unleaded Premium in my 280 SL, beginning when it was new in 1971, with superb results at two different octane ratings (for California and Louisiana). I was then, and have ever since, been discouraged from using any additives with premium fuel in the M130 powerplant.

Joe Alexander: All Mercedes automobiles manufactured after the early fifties were manufactured with superior valve seat and valve materials. Most experts feel no additives are needed for non-leaded fuels. However the prescribed octane rating for even US cars was 98 (Ron)! so in most cases today most engines must be slightly detuned. Timing can be retarded slightly to compensate. The factory manual states 1 to 2 degrees for every octane lower. 6 degrees is the maximum decrees in timing reccommended. Generally speaking do not use below 94 or 93 octane RON fuel in your car.The compression ratio of your engine is cast into the cylinder head of your engine between spark plug 2 and 3 (below the cylinder head number. It most likely will be 9.5 on the 280-SL 113s unless you have a special low copression engine. The 113 US cars after 1968 were slightly de-tuned for emmisions. These engines had some slight changes in timing and injection. The camshafts in the later 113 european delivery cars was a little hotter. Drastic power robbing emmission changes did not occure in US cars until late "74" and "75" when compression was lowered and catalytic converters were added. The major engine components (block, head) in all the 113 engines european or US were basically the same. In reguards to your starting problems; make sure your car is in good tune first. The fuel filter must be clean and the engine air filter and the injection pump air filter must be clear also. US engine cars around 1968 and 1969 with injection pump ID #R20 had a cold starting aid with a starting solenoid on the injection pump controlled by a coolant sensor on the engine and an electrical relay near your brake master cylinder. This system enrichened the injection mixture during cold starting or when your car was hot. The latest engines with the #R22 & R22Y pumps did not use this system. Operation of the system should be checked when the engine is cold and hot. Also the starting solenoid on the intake manifold should also be checked. It will squirt additional fuel into the intake manifold as required for starting. This unit should also be checked for leakage when not activated. This unit was altered also in later engines with the #R22 &R22Y pumps. Lastly Mercedes improved the "ball pressure valves" in the later injection pumps. These valves prevent bleeding back of fuel from the injection lines. If these are leaking back some start-up problems may occur. See section (07-11/2) in the workshop manual for more information.

Fuel economy

I thought I'd throw out some recent mileage figures for general info. This was pretty much highway with some town driving and quite warm temps (+90*F). 2 fillups that I did myself to be sure the tank was full. 362.4 km(225mi); 40.5lt.(8.9cdn. gal.) = 25.3mpg (20.22mpg US) 413.8 km(257mi) 45.6lt.(10.cdn. gal) = 25.6mpg. (20.5mpg US) We traveled at 60-70mph and I think I have 3.69 rear end. How does this compare with others experience ?

Richard: 1971 280SL, 4 sp manual, full of emission devices: New York City, about half city and half 55 mph highway: 15 mpg.

Tom Sargeant: 20 US MPG is pretty strong. Couple of questions: auto or manual trans? Any US emissions controls? Top Down or Up? Hard Top on? Engine been rebuilt? Here are some stats on one leg of my trip to Columbus Ohio. I used a hand held GPS navigation unit to capture average speed and mileage, so I am reasonably comfortable with the accuracy: Trip report (return trip only-messed up my navigation on the way up): Total miles (one way): 435.0 miles Average Speed: 66.5 MPH Mileage: 15.1 MPG Moving Time (FYI): 6 hrs, 31 minutes Auto Tranny, 71 emissions control, top down, AC Off, wind screen on. Engine is original except new cam and rocker arms. Valve lash reset recently at (inches) .007 and .003. I know that my timing was not quite set right for the trip, and I think I used about a quart of oil over the 900 mile round trip.

John Hassle: my average mileage over 6,400 miles was 18.1 MPG (US gallons). My average speed on interstates/freeways was about 67 MPH (with spurts up to 90 - for passing, of course). Engine was completely rebuilt about 2,800 miles before the trip. Oil and filter were changed the day before the trip began. Total oil consumption was about 0.75 US quarts over the entire trip (essentially a new engine). Transmission: 4-speed manual. Hard top on. Tire pressure: 30PSI. AC: used about 25% of the time (Fridgeking converted to R134a). Cruise control used virtually all the time on long stretches of freeway; overall about 50% of the time. Basic theory of gas mileage: Mileage is inversely proportional to weight of foot.

Dan Caron: I got 25MPG ( about 20MPG American ) in a 250SE Coupe once with four people and a nice steady 3,000 RPM. That is until the engine blew up.

Cees: I get consistently around 17 MPG (US) or, in european terms, around 7,5 km to each liter. That's with an automatic 280 SL (no emission controls) and a 4.08, now 3.69 rear-end (I have the 3.69 in for a few months now, but I don't notice much difference in mileage terms). My engine is tired and needs a rebuild, consumes oil at around 1 liter per thousand km, yet runs strong and not fuel-inefficient. I drive mostly highway, at an average speed of around 75 MPH. From looking at an official MB publication (I believe the BBB) it shows that the mileage is influenced very heavily by how fast you drive. So a hint could be: try a tankful driving around 10 MPH slower than you normally would, you should see a noticeable improvement in mileage. I understand from other owners that 16 MPG is not unusual at all.

Cees: when I limited my top speed to around 65 MPH (rather than the usual 75 MPH) my fuel mileage went from 1 liter per 7 km to 1 per 8. I think that equates to going from 16.5 MPG to 18.8 MPG (USA gallons).

Bob Smith: that is really good fuel economy. I am doing an ongoing Economy study for my 250SL. Let me tell you I think my car is a "PETRO-HOLIC". Recently I did a short trip to the country (140 miles) and it guzzled its way through 44.73 litres. It returned 11.85 US MPG OR 5.04 KM/L and that was an improvement on the economy from the previous trip, when it returned 9.28 US MPG or 4.56 KM/L. I think it is in tune and not running rich. The exhaust is clean and has that nice dull charcoal colour. There is no petrol smells from leaks. My car was not being driven for almost 2 years before I bought it this June, so maybe as I drive it more it will clean out and the consumption will change for the better.

I drive my 65 230SL (4 speed) regularly and estimate my around town gas mileage to be about 12mpg. I don't necessarily horse the car around, just drive normally. On the highway probably 15-17mpg. Other cars of this era also got lousy mileage.

For the better part of 150,000 miles, covering 32 years - with the old-style leaded fuels and with the current types - I have consistently gotten @ 11-13.5 MPG (US). I will admit to driving the car a bit faster than the average car on the road, and accelerating quickly, but it seems to be returning the same range of fuel useage more or less regardless. When running fast over uncrowded highways (@ 75-85 MPH) I do use a bit of oil as well, though nothing too serious (and well less than the guide range in the owners manual). Frankly, I cannot imagine getting over 14 MPG, unless one drives like my Aunt Lucille!

Albert - I have just done a travel of 2.850 km (around 1.780 miles) in 6 days. Most of them (2.350 km) by highway at cruising speed between 110-130 km/h (69 - 81 mph). The average consumption was: 10,8 liters/100 km (21,8 mpg). The total OIL consumption was 2,8 liters (1 liter per 1.000 km), is it normal? The engine was rebuilt 6.000 km (3.750 miles) ago. Someone told me that these engines usually consume some oil even from new (in the owner's manual you can read it), but another Pagoda owner (250 SL) told me that his Pagoda consumes much less oil ?? I drive my car usually on twisty roads and highway at higher speed, and then the fuel consumption is around 13 liters/100 km (18,1 mpg). Regards, and donīt worry about the fuel consumption: we enjoy each liter/gallon we use!


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